The AI of DOOM (2016) | AI and Games #30

[@AIandGames]

Eight years in development, 2016's DOOM was a long awaited return for the franchise. I take a look at the AI toolchain adopted in the game, where it comes from and the secrets that reinforce the game's 'Push Forward Combat' philosophy. DOOM is one of my favourite games of the last ten years, much less 2016. So working on this piece has been a real pleasure. Thanks once again to my sources who came forward to discuss their experiences working on DOOM over the years.

[@dml09]

Great video. Even have watched the GDC presentations, you added in some information I wasn't aware of.

[@IuliusPsicofactum]

I loved the video.

[@trollpatrol1177]

I wonder if it's possible to modify this token system to allow for more demons to attack you at a given time.

[@KenFung]

Stop using the word "Fun". Quantize Fun please! You are suppose to be analytical not objective.

[@Tsinij]

Fantastic explanation. One question though: do you have AA disabled? Or is just some weird super-sampling issue? All the shots of DOOM (4) look too sharp and rough around the edges.

[@fare-5174]

The ticket thing is hilarious. "I kindly submit this form to hell authority for permission to take a shot at the Doom Slayer in the next two seconds, filed in triplicate and signed by the senior demon responsible for this area".

[@janbosch5951]

And then a Hell Knight just comes in and streals the token. "Gimme that ya lil S&*T!"

[@Warhamer116]

@Alex let's face it, would it be a 'hell' if there wasn't?

[@2yoyoyo1Unplugged]

@@Warhamer116 Bureaucracy is one of the greatest breeding grounds for evil there is.

[@michaelstein7510]

@@2yoyoyo1Unplugged I bet the bureaucracy in hell is still easier to deal with than the DMV.

[@Lawgamer411]

Even the dev team hated what they were working on; “Call of Doomy,” amazing how they realized it and made something incredible.

[@Ostsol]

The trick is convincing the people in charge.

[@xlawxc]

My favorite thing I learned in this vid is the difficulty of doom isn’t governed by buff enemies, nerf player. No they give the enemies more resources to use against you which is how it should be.

[@someguyidk7823]

They also buff enemies and nerf the player Still, its good to know that we can start seeing buffed ai these days (civ5 diety im talking about you)

[@distantsea]

Resident Evil 7's Madhouse difficulty does both and really well. It's the same area, but different encounters, and you're weaker.

[@etlttc353]

@@distantsea harder enemy Less encounters

[@GallowayJesse]

I actually prefer things to be the other way. I think players shouldn't be short-changed in terms of what the AI has to offer just because they aren't playing on the highest difficulty.

[@hungryalien8494]

@@GallowayJesse Well, if you're playing on lower difficulty, you're asking for a moderate challenge. So it's kind of logical to have AI not fighting at their full potential. In a way, it encourage players to replay the game at a higher difficulty to play the game in a more intense way. Buffing ennemis HP and lowering player HP is just artificial difficulty. You're just playing the game the same way as in lower difficulty, but it will take more time to finish it. It will tolerate less mistake from the player, but is still the same as lower difficulty.

[@tenchimod]

I had no idea that the demons used attack tokens. It sounds like a fantastic mechanic and worked well in the game.

[@notapplicable7292]

The to me sounds like some of the best most in-depth ai you have featured thus far. I love that their ai is designed not to be noticeably cleaver but instead to act in ways that allow the player to have more fun.

[@CaveyMoth]

My favorite factor of the AI animation in Doom 2016 is focus tracking; Looking at the player all the time. I hate games where the AI opponents lumber about almost at random, going through simplistic attack animations while they stare off into space, as if they aren't even truly in pursuit of the player. And when the player dies, they just keep swinging their weapons clumsily towards the corpse, not even acknowledging that it's dead. BLECH! No immersion.

[@dml09]

Yeah, and the enemies effectively glory killing you when you die to a melee (and even some differing death animations from projectiles) is a nice touch.

[@SuperCharleh]

Video just outlines how much work goes into making this game fun/amazing that most people won't appreciate.

[@sam_making_games]

Having the AI look into player direction is pretty easy from my Unreal Engine 4 Experience (2 months...). Just call SetFocalPoint on the AI controller and pass it the players location.

[@CaveyMoth]

That's pretty cool. Didn't know it could be that simple. But then don't you also have to get animations for posture, so the pawns will orient themselves towards you, instead of just rotating in place, Minecraft style?

[@Questar_Valdamar]

I always thought that enemies attack player corpses because they just hate us that much. :P

[@AHeroAlmost]

I think it’s the music in Doom that makes me want to keep going forward... makes me feel like a bad ass with the music blaring in the background

[@The28studio]

AHeroAlmost combat design+ music, perfect recipe

[@taumil3239]

After finishing the game I actually didnt like it that much, but music was the one great thing about it lol

[@ninetailedfox579121]

I think the music design in Doom is he best I have heard in any game.

[@LJboochaa]

Kupo Warkson pretty sure some guy made a video about the doom soundtrack that is fucking great

[@schneggen_schubsa6896]

@@LJboochaa i think the yt channel noclip has a three piece documentary on doom 2016 and one part is dedicated to the Music with interviewing mick gordon the composer

[@turbulancemusic4830]

Can we take a second to appreciate the masterpiece that is dooms soundtrack?

[@AAAAAA23485]

Oh yeah yeah

[@clintonbyers930]

@ItmustbeF8 you forgot titans realm

[@ridleyrickmanreduz2196]

@@clintonbyers930 and rip & tear

[@The0007rishabh]

Mick Gordon the 🐐

[@mehmetakyuz5290]

Aand its even better with Doom Eternal!

[@musthavechannel5262]

12:12 "...weighted distribution of shot accuracy. Whereby ememies deliberately miss when you are moving top speed", while video shows the fireball missing a stationary player 8 our of 9 times.

[@dml09]

A good point, though this is highly likely a customised scenario for the GDC presentation. It's easier and more obvious to display this deliberate miss percentage when the player is moving slowly, so they likely designed this example with that in mind. Perhaps on the lowest difficulty this might actually be an accurate representation (though I never play at that difficulty), but I can assure you on nightmare / ultra-nightmare that the Imps are very accurate, and even linear movements at full speed aren't often enough to dodge their fireballs.

[@AIandGames]

Indeed you're correct. It's a demo put together for the GDC presentation to show how a moving character (who is moving *very* slowly in that example) will result in the imp missing its shots.

[@alexbranch70]

@@dml09 I know how you feel, if anything on those difficulties they will plan where your gonna move and yeet a fireball *in front* of you.

[@yazman4040]

That was unexpectedly AWESOME. I wasn't expecting to understand let alone enjoy this break down of the ai. Thank you so very much!

[@fartthug27]

What the fuck are u holding

[@yazman4040]

A very tiny pumpkin.

[@lordterra1377]

+Chester Yazwinski LMAO!

[@Giraldtec]

The idea of the tokens is really good!

[@clockwork204]

Right? I found that token bit in particular to be pretty clever. :D You can wade through hordes of demons, without being too overwhelmed. They could also probably just adjust the number of tokens available to make the game / encounter harder without straight up doing something as artificial as pumping up demon stats.

[@bojackhorseman4176]

That's exactly what they do actually. There's way more available tokens for demons to utilize in harder difficulties. That's not to say they don't buff their health and damage, though, but it's not just that, and that's why it feels way better than what most games do.

[@UNSCPILOT]

@@bojackhorseman4176 In essence, it makes it feel like they are getting smarter and more aggressive on top of being tougher, instead of just pumping toughness and damage up to unreasonable levels

[@Ochatach]

Whoa, thought it would be a long drawn-out video when I saw it was 20 minutes but it went by in a flash. Really interesting and good pacing of the talkingpoints, really good edits showing off the maps and functions of the AI. Thank you for the video :)

[@Aryzon13]

"Demons check the environment to not clip through walls and will miss more when you move." Cyber Mancubus: "What is missing?" Baron: "What are walls?"

[@ZeroThe2nd]

Totally loved the video. I've been putting quite a few hours in DOOM single player, but never expected the systems behind it to be so deep and interesting. Thanks for the amazing video ^-^

[@TimTams_64]

Who is hyped for Doom Eternal?. also dont question why ammo and health drops from demons, games are not meant to make sense.

[@nemeru3352]

Games don't have to make sense if its in service to good game design, rather than needleless realism

[@FreakingTheFreak]

Oh the health is explained in the lore itself. One of the first entry about the doomslayers armor says something along lines of "having the ability to absorb argent plasma" meaning he heals and sustains himself by killing demons. He literally keeps himself alive through sheer rage and hatred. Pretty metal

[@Zaprozhan]

By attaching ammo and health to demon death, it serves the Push-Forward! principle. Wanna live? Gotta kill!

[@TimTams_64]

Theg ame mechaic is obvious, iam talking about how it applies to lore.

[@fieldy409]

He was given power by a seraphim to absorb 'power' from the demons. Thats vague enough to possibly mean hes somehow forming dead demon energy into ammo somehow

[@memyselfi9270]

Awesome video, you even talked about the awesome Imp behaviour

[@elektra81516]

What I love about this channel is you make these videos for AI enthusiasts and programmers and not your average gamer who has no idea what an FSM or an editor is. Superb work!

[@salsamancer]

I love the unapologetic gameyness of Doom 2016. It actually reminds me more of character action games than modern FPS games. It has all the same hallmarks: levels designed around the ebb and flow of combat arenas, fast paced action built around maintaining the flow of action, and smartly designed AI that knows when to be passive and when to push back giving the player the illusion of overcoming overwhelming unfair advantages

[@StephenBarr]

Great video. There are so many interesting things going on here. Started Doom twice and never got around to finishing it. I need to try again!

[@AIandGames]

DOOM is one of the few games in the last couple of years where I didn't stop to question 'how did they achieve X/Y/Z?'. I was too busy having fun. That's a rare moment for me these days.

[@JEL625]

Rip and tear until it is finished

[@mbe102]

Damn, D00M on a controller looks like Doom Slayer is wearing a straight jacket.

[@LochyP]

Stadium ARTs he's just got the sensitivity on low mate, controllers aren't that bad for doom

[@lt3880]

i play low sens, 0.8 in game and 1600 dpi. this is a controller. you can tell by how much start-stop motion the cursor has and how it moves mostly in straight lines as opposed to smooth curves.

[@ChadicusThunderCock]

Stadium ARTs depends who is playing with the controller

[@LochyP]

L T sorry, I was unclear, yeah he's clearly using a controller. I meant it's not that bad to play with, as long as you increase the sensitivity a bit, and clearly it's default in the video.

[@LiveforHM]

TopDog Stargazer nah the input method definitely matters

[@unfa00]

It's fascinating how the AI is programmed to give players a fair chance in the fight, and coordinating together to not randomly overwhelm them. This was a really interesting insight, thank you!

[@baronsengir187]

Never understood the hate Rage got. The AI was so much better than anything else we got in other shooters.

[@pixlman]

Not really? It was either guys who shot from cover or melee mutants that b line towards you.

[@baronsengir187]

Of Course the Zombie type did. They are Zombies. They act like it. But later you get enemies who circle you and use the Terrain very cleverly. And they changed behavior on where you shot them. That is far more than other shooters did and still do.

[@pixlman]

I finished the game a couple of months ago and that's not how they worked. Melee types (both human and mutant) just ran at you waving their clubs, and shooter guys (both gangs and Authority) stuck behind cover and shot, occasionally throwing a grenade. Big gunner guys and shield guys just stayed out in the open. You could throw a grenade at them, causing them to scatter and find another cover spot but that was it. I think you're confusing the way they animate and interact with the environment with actual intelligence. RAGE had this blend of physics and animation that had enemies reacting to where you shot them and blending that with their current animation, which is still something not many games can brag about. But as for behaviours? The most they would do is shoot from the ground if they got downed.

[@baronsengir187]

Then you played a different game than me. It was not F.E.A.R. Level AI but close.

[@pixlman]

SengirShowsU apparently I did. Anyway, my biggest problem with RAGE wasn't the AI, which still put up an OK fight, it was just that the game was boring for me.

[@TheRiptideRaptor]

The DOOM GDC talks were really nice, so I was waiting for this

[@restlessfrager]

Oh my god i can't wait to repeatedly chainsaw through Arch Viles.

[@michaelwarner7311]

restlessfrager imagine chainsawing the arcnotron

[@thelivingglitch307]

Summoner's are so much I like them, I feel like they are the new Arch Vile's.

[@mohitnaidu6219]

and I can't wait to crucible sword their asses.

[@kveller555]

I have a feeling the Arch-Vile is going to be a boss fight.

[@AAAAAA23485]

@@thelivingglitch307 the least they don't burn your ass down all the time

[@Tezcax]

Interesting. It looks like the original Doom 4 would be a terrible game, filled with cliches. Instead of good ol' rip and tear.

[@udittlamba]

The call of doomy would have turned out to be a forgettable brown filter cod clone.

[@THExRISER]

14:09 Nice editing. Great video though,I genuinely learned a lot,thank you!

[@xyzz8722]

Some facts. - All games post Doom 3 are based on that code. - Doom 3 used a scripting language for AI (similar to CPP) it was interpreting events from the game code. But you needed to write it in notepad. - Sometime either Quake Wars or Rage. They kept the script for prototyping but eventually all the scrip written stuff would be compiled in its own dll called superscript. Id still sticks to the classic route if it aint broken dont fix it and it works perfectly. Acrually as far as at least Doom 3 there is code for AI that dates back to Hovertank 3D.

[@SyThiCProductions]

12:17 really thank you for the little yellow subs, sometimes I hear people saying something but my brain just doesnt get it. dumbing it down in little text is INCREDIBLY helpful. thanks for the awsome video. u earned a new sub dude

[@Beestification]

It's kinda sweet. There's this veritable symphony of discussions amongst demons (whose job is to kill you) and with the engine, all tailored around you the player so that you're having the best time they can give you. It's fascinating to see that there's so many other processes at work rather than just controls and graphics. What a great channel!

[@kevinbouquet4480]

Great video ! I loved Doom 2016 ! Tough, I was surprised that in your pillars you mentionned "Power" because to me the "Power" given to the player is a combination of 2 others pillars : Speed and Distinctiveness. I'd say that the fourth pillar is the Level Design itself. The arenas of Doom 2016 are structured to give the player a fluid mobility and flexibility to kill the demons. And not to forget the secrets in each level. So maybe I'm wrong and I didn't fully understand what you meant when you said "Power" but I really think that the Level Design is a part of that combat pillars. Anyway, nice vid and I love your work !

[@Twitch375]

Fluid mobility and flexibility. Those fit the pillar of speed & arguably power. Levels are designed for speed & easy access to your next kill to feel powerful. Level design itself is waaaay too vague to be used as a pillar. If someone asked you what Doom is about in a couple words, what would replying "level design" tell them opposed to "power" and or "speed"? Level design in Doom is very good sure but only because the level makes you feel like a parkouring demon slaying badass. I guess what I'm trying to say is level design can be drastically different depending on the game but speed and power are tangible themes that can be applied to just about anything.

[@Lugbzurg]

Yeah, really. I was thinking that "Individuality" and "Distinctiveness" shouldn't have been separate, but rather the same pillar, as they both serve the exact same function, just for one being towards the enemies, and the other being towards the arsenal.

[@ninetailedfox579121]

I think what he meant by power is that weapons feel not only distinct, but also strong. Things like being able to kill even the strongest of enemies in 1 or 2 Gauss Cannon rounds as opposed to just making all the enemies be bullet sponges.

[@ui6144]

Excellent presentation of analysis in conjunction with developer feedback, always find these videos both amusing and enlightening.

[@fella11814]

Awesome video. I feel like I've really witnessed all these components you discussed working together in the game without knowing it, but know that you've shined the light on the matter it's really fun to think about and watch while ripping & tearing. Cheers to the ID team!

[@renegadeguy2340]

DÜÜM

[@ViskayaNuebler79]

Fascinating. This is one of my favorite games and it''s no wonder the gameplay runs so smoothly and intuitively!

[@YonatanAvhar]

The editing of the intro was incredible!

[@jcmo5900]

Well done. I loved this game, and have been waiting for you to come around to it ever since release! I really enjoyed learning about the wizardry behind the scenes - thank you.

[@Sizifus]

DooM 2016 - Feel like an unstoppable force DooM Eternal - Earn your status as an unstoppable force

[@Duckspeak]

I love the technical analysis. Lots of youtubers are afraid to get too tech-y, but this is amazing. Keep up the good work!

[@mikeuptonphoto]

Brilliant video! I had no idea the amount of work that went into the AI in DOOM. Thank you for this!

[@Orzorn]

Absolutely criminal this only has 93k views. What a great video and explanation of what makes DOOM's AI so great.

[@projectill]

I had no idea such complicated systems run in the background. thx for the video

[@jdmaine51084]

This is the most insightful video I've seen in a long time. Using a master token system to allow enemies to attack is genius. Again, something I could see being controlled to vary the difficulty level... the higher the difficulty, the more available tokens, the more enemies can attack the player at any one time. Brilliant, brilliant idea.

[@ChrisSmout]

Fantastic video and some great insights behind the game. Thank you for taking the time to explain this in an easily digestible fashion.

[@JayLeu]

That intro by itself was enough for me to give a like. I'm only a minute in and I love the editing and voiceover.

[@SpacialKatana]

Good, concise breakdown of the game's AI . I'll be checking more of your vids soon. Cheers Tommy !

[@lipeckih]

A couple of things stated here I did not observe during my own playtime in the game (cacodemons always tried to get into melee range with me and infighting seemed to trigger only in a few pre-programmed locations), but this is still a very informative video. Thank you.

[@genericsavings]

The AI is excellent in this game. I had a Hell Knight charge at me and I retreated onto a lower level. Instead of making a beeline for me, it changed up and tried to flank me from the side. Great game. Great video.

[@TheJege12]

I absolutely love this video, oh my god Gonna watch all of them!

[@PhatToni]

This is the first time I have heard anyone talk about the animations in Rage....So far ahead of its time. The blending of animations makes combat so much more immersive...glancing shotgun blow to an enemy charging you..doesn't put him down but he reacts while still running. Very interesting to hear an in depth explanation of the workings, thanks! Subd

[@ScoutOW2]

Wow this is perfect! And perfect timing too! Thank you so much!

[@dropfacades8142]

Great video man! Love these types of exploration/review examinations. Cant wait until Eternal!

[@24YOA]

You guys nailed the starting to this video, 10/10

[@dylanmcnab2980]

my favourite moment with DOOM ai was when i got the berserk powerup the imps started to run and we fell into a dark hole. After this i just started chasing down this group of imps in the dark killing each one. it honestly felt like i was the monster in a survival horror game, it was awesome

[@SdisticDrummer]

First video I've seen of you'res... Love your breakdowns and technical discussions about the game.... I'll be subscribing and watching more... Keep it up.

[@gardenprogeny1141]

great video, made me appreciate this masterpiece even more than i already have

[@supofgaming4693]

Excellent video. Really interesting seeing the interactions of the different systems such as the Animweb and comparing that to the final result. Keep up the good work :)

[@jowdaysimgen4450]

Beautiful. Great work mate!

[@TheHotdogstand]

Wow this is an awesome video and I’ll be checking the rest of the Chanel out! I’m studying CS right now an I like how in depth you got about the AI decision process. The token system I thought was especially interesting!

[@damienrodriguez4453]

This is genius. I'm so happy i decided to look into these kinds of things

[@GTCvDeimos]

I literally just uninstalled doom after completing my Ultra Violent playthrough..... [hits install] (side note: great intro, Tommy!!! Very well edited! I may have watched the first 90 seconds several times over)

[@Arcodus]

This was a good, informative video :) I don't recall 20 minutes passing this fast before!

[@palaceofwisdom9448]

Great video. The best AI goes unnoticed, and this helped me appreciate the effort that went into making this game work so well.

[@Roberto-tg9xf]

WOW!!! , it's really amazing. I am the programmer of the mechanics of the enemies and your video has helped me a lot. Congratulations.

[@mftripz8445]

Lmao damn buddy you contradicted yourself in a single sentence

[@morbid1.]

Can't wait for "hell on earth"... they should show something at Qcon

[@zerotactix5739]

They already confirmed they will be showing DOOM Eternal in Qcon

[@mikerelf]

There's gameplay reveal on 10th of August.

[@bigbaddymike3101]

You asked, and Id delivered.

[@lividsphincter4098]

@@bigbaddymike3101 Yeah right off the bat they show a grappling hook and that's all I need to see to know it'll be good.

[@seannotconnery8191]

livid sphincter Only id could concoct a shotgun grappling hook designed to pierce through demons like butter and use them as an anchor point.

[@HartleySan]

That was really fascinating and interesting. I'm always amazed at the amount of technology and effort that goes into making games like this. Really amazing. Thanks.

[@SylvesterAshcroft88]

The pacman comparison is interesting, as i remember doing a game design course a few years ago, whereby we used a sprite, of a lost soul to create a pacman style game.

[@mrb4862]

Excellent video. Thanks for this.

[@zelest]

I had no idea about the token system, that's actually quite genious.

[@patricksketch2003]

As a starting programmer and game dev I am impressed and fascinated with dooms ai and it makes me wonder what else we can do with those old tools

[@GraveUypo]

HFSM is exactly how decorate works in zdoom too. cool to know.

[@BackfallGenius]

That was hugely informative. Great video!!

[@EricRidesDirt]

It's amazing how many different systems are all working under the hood to make this game so fun.

[@turntyle]

this was a really fascinating video! subbed!

[@kajito]

This was really interesting. Great video !!

[@drezee7173]

Thank you for the video! Quite informative and curious how these concepts I've come across some of these concepts from other areas

[@TheKodiah]

What a great video! Definitely did your research!

[@RatentaisouFGO]

HOOOOOOO BOY, gtg grab some popcorn.

[@Crowbar]

What was the most interesting for me in this video is that difficulty levels apparently affect way more than just health and damage of enemies, which I didn't expect. That's cool.

[@08-145]

I love this series.

[@GrizzleMarine]

Hey man might be a shot in the dark but love you understanding and passion for the AI in games like Doom and how epic they are. Myself and a few other nooby but passionate developers are working on a passion project that we would like to incorperate AI wildlife and monsters within the game like Doom. If you fancy just hearing me out on it and fancy working on somthing like this please feel free to hmu.

[@Edbrad]

Found this video on August 31st 2024. Amazing that now Google just made an AI that can generate real time Doom 1 in interactive video. Crazy. Imagine playing this version of Doom with full music and sound

[@HughGBols]

Amazing, as always!

[@fartthug27]

Hugh G. Bols congrats in being frist

[@KevinCastillo-hh1fn]

Awesome video :D, lots of interesting info thanks

[@artorias-24]

Great video and very informative. However I think you forgot to mention that Doom 2016s AI actively tracks the player and “predicts “ where the player will go next and attack in predicted location instead of attacking the player. For example hell knights will sometimes do a leaping ground slam towards where the player is going thus predicting the players trajectory and direction they are going. Same goes with imp fireballs. They attack in the predicted location so that if the player continues going in that direction at the same speed they will 100% land the hit.

[@ItsMrFresh]

Great video, really fascinating :)

[@dnjtejgpf]

Another informative documentary. Thanks!

[@MrTeaboar]

I'm not into programing and stuff, but this one blew my mind. I wish someone would make a doom environment design analysis as well in this quality.

[@terminat4028]

Cool video on one of my favorite game! Thanks for all the infos! :)

[@aegispopeellis]

Great insight - thanks for the share

[@ShadowWolfTJC]

You know, while neither Tower of Guns, nor the recently-released Mothergunship, have glory kills like Doom 2016, both of those games have a gameplay system that feels similar to Doom 2016's Push Forward Combat system, where enemies drop lots of pickups upon death, but those pickups disappear over time, forcing players to often embrace a style of combat where they must rush close to their enemies in order to pick up all the goodies before they disappear..

[@slaytonpeale9727]

Imps have a pretty two-way standard when it comes to combat. Some will try to get range on you, some will run up and try to slash you. Cacodemons will always try to get closer so they can use their teeth, which does significantly more damage.

[@LittleRainGames]

I subscribed before the video started, some how knew it was going to be good.

[@vayneinsane]

As someone who's attempting an Ultra Nightmare playthough this was an extremely insightful episode and how the hoards of hell work underneath the hood.

[@AdamJee923]

Great in depth video thanks

[@bliglum]

Doom 2016 was and is epic goodness.. One of the few games that manages to deliver both awesome gameplay and awesome graphics.

[@MeniscoManeiro]

I can't wait to see some kind of ''scare'' A.I on doom eternal, like demons running from the slayer when he's enraged

[@mftripz8445]

But demons aren't supposed to be scared of anything, because it's a demon... If they were scared of doom guy then doom guy is the demon lmfao

[@MichaelVir]

FEAR is a great example of using finite-state machines in ai.

[@mana20]

Would love to see a follow up for eternal

[@saturdaynightgaming4783]

I love the ai in rage. On the higher difficulty they will does more and even throw your boomerang back if they catch it. Jump off walls to avoid your gunfire and boomerangs etc.