This is something I've been wondering about recently. It seems in recent years that AI in games hasn't been a major focus for most developers. It seems to have taken a pretty solid back seat in the priority list to graphics and, rather than improving AI for single player games, we have instead seen a trend with multiplayer elements being incorporated into games instead. (obviously that is debatable, but just my take on it)

So anyway, I am wondering what are the stand-out games for you, in terms of AI? What games do you consider 'best in class' for AI for the various genres?

For me, there aren't too many games that really stand out as making me think "Wow! The AI in that game was amazing!". I remember being impressed by the AI in the original Close Combat games many years ago. It seemed to have a really cool and innovative morale system, where your soldiers have minds of their own and would even refuse orders or run away, if you told them to do something obviously suicidal. I remember some of the Tom Clancy games also had pretty good AI and Half Life seemed to have good AI for its day.

I'm playing Batman: Arkham City at the moment and I have been quite impressed with the enemy AI there. If you're trying to take out a room full of thugs and they detect you, they will start hunting for you, using thermal goggles etc. I like the way that, if they feel threatened, they will start patrolling back-to-back, to make it more difficult for you to sneak up on them.

For RPGs, Oblivion seemed quite impressive with it's full NPC scheduling and the way NPCs would chat among themselves. I'm sure a lot of later games have copied that formula. I think Ultima VII had similar NPC scheduling (although the combat AI for player-controlled NPCs seemed a bit poor).

Any thoughts?

Dragon Quest 4's ally AI was really good for its time, even if it cheated.

Knights of the Chalice has really good enemy AI, to the point where I think the game should have included an option to tone it down. (Call the option "difficulty", and have the only effect be to change how smart the AI is. It can be done, as I stated in another thread; Puzzle Quest did this, for example.)

Alien Isolation

XCOM, F.E.A.R., A Song of Horror (impressed me with its randomness and reaction to the playstyle of the specific player) and Alien Isolation are all games with imo really good A.I.

The AI is actually a dual AI operating on diffrent levels, making the Aliens really tense and you fell haunted and on te edge. I dont know how to better describe it, but if you havent played it and into these kind of games I really recommend cheking it out you will see what I mean than.

- Another shoutout for the enemy soldiers in FEAR.
- The AI in Dawn of War, especially with the AI mod is pretty good.
- In the genre at least, especially at the time, I believe Desperados had pretty good AI. Better than Commandos in any case.
- The guards in Arkham City (and Asylum?) behave in a very believable way, that is apart from not running away the moment they see Batman!
- I think the STALKER series has some pretty impressive AI as well

Last but not least, Dwarf Fortress. The degree to which dwarves interact with the world and each other is insane.

The first two Thief games (and by extension System Shock 2, since it uses the same engine).

Hey, I get to copy-pasta a post I just made in another thread. Two birds with one stone, definitely not self-plagiarism

I remember a phrase I heard a developer use - "artificial intelligence is easy. artificial stupidity, on the other hand..."

FPS, bots in all Unreal Tournament games in general are extremely good. I never get bored playing them. You also get to choose from a ton of difficulties so everyone can find their optimal spot. Important to note though that on the 2 hardest difficulties, the AI start to cheat a little (on Godlike, bots have 360 FOV, meaning you can't ever get the jump on them). The last "fair" difficulty is Masterful.

For RTS, Starcraft II is pretty good. On the hardest difficulty, the AI even prioritizes support units, finishes off low health units etc. (in campaigns, never played a multiplayer match). Too bad the highest difficulty also forces you to play on the highest game speed....

Turn Based strategy, Etherlords 2 can be pretty difficult on the highest difficulty. You have to think of/change up your strategy for many fights depending on what the opponent does and in general, the AI tries its best to win I feel.

It's like that in chess as well. Making a chess AI that can beat the World Champion is 'easy' (i.e. they can use computational brute force and accuracy). However, making a chess AI that plays like an average wood pusher down your local club, overlooking things and making a bunch of 'human errors' is much more difficult!

Chess AI has advanced to the point where even human grandmasters are not willing to play against computers in tournaments.

It actually has gotten to the point where researchers have, instead of just trying to make the computers even better at chess, started to study how to make AI that's more fun to play against (and hence would be more suitable for casual chess computer games).

https://techxplore.com/news/2021-01-chess-sacrifices-mastery-mimic-human.html

Also, a good quote from the article:
"But we had to be very careful—you have to make sure it doesn't search the tree of possible moves too thoroughly, because that would make it too good."

not hearts of iron 4 thats for sure

Yes, for sure the main challenge with AI is designing something that feels like playing against a human, not like some flawless, omniscient, impenetrable wall.

See also Tic-Tac-Toe. It's really easy for even a human player to get good enough at the game to never lose; you can easily find instructions for how to ensure that. To write a Tic-Tac-Toe program that a human can play against and win can be tricky, though I have a suspicion that random moves might be reasonable.

Perhaps the ideal Tic-Tac-Toe AI would be something like this:
* If the player would be able to make 3-in-a-row on their next turn, move to block it. (If there's more than one way, then the AI can forfeit, or alternatively make a move and let the player win.)
* Otherwise, choose a random free space and move there.