Artificial Stupidity / Stealth-Based Game

• Batman games:
  • In the stealth sections of Batman: Arkham Asylum, the Mooks rarely ever bother to look up. It's a little bit more frequent in the harder difficulty levels, but still. And then there's also this. They also have no peripheral vision whatsoever, except for the insane inmates who have a perfect line of sight. If it wasn't for their constant conversations, you'd assume they were all deaf, too, given you can stick one of them in a Dragon Sleeper (complete with barely muffled groans) with their buddy none the wiser ten feet away. Lastly, it's very possible for those inmates to run into obstacles, each other, or to trip on scenery trying to get at the player, causing them to knock themselves or other insane inmates down for an easy knock-out.
  • In Batman: Arkham Origins, they'll notice that you're using gargoyles or similar wall decorations and take them out... or, to be more accurate, they take out one gargoyle, two at most, before getting bored.
  • Weirdly enough, Origins mooks, who will take out Sonic Batarangs with assault rifle fire, are smarter than the chronologically later ones in City, who will walk up to a mysteriously pulsing bit of Bat-Technology and attempt to step on it. This means that arranging "surprise parties" (with gifts of blunt force trauma and time in prison hospital) for mooks is a lot easier in the games when Batman is more of a known quality, when they should have figured out after a few years that anyone setting off alone to look at the bat-shaped bleepy thing is coming back with a concussion.
  • The final level of Batman Beyond: Return of the Joker on the Game Boy Color has gaps in the floor in some of the places you fight enemies. The AI is not programmed to recognize that there are gaps in the floor and will walk into the gaps to their deaths en masse. In Dark Lord Jadow 1's review of the game on Youtube, he got 30 enemies to walk into gaps and die in a single playthrough (See here).
• In Hitman: World of Assassination Trilogy, NPCs have a predictable reaction towards bullet impacts. When Agent 47 shoots twice in a specific area or hit a non-vital body part with a silenced weapon, people will go in a panic state where they are distracted towards the point of impact, all while keeping the titular character free from onlookers. Guards have an additional behavior with a third shot, where they will head straight towards the "dome" or area from where the shot came from (regardless if the weapon is silenced), ignoring everything in their way. This means two things: as long as he immediately leaves the "dome", Agent 47 will not be suspected by the guards; and that Agent 47 can practically waltz into restricted areas because guards won't give a damn about him, even as he strut in front of their vision. It is hilarious how one can get a Silent Assassin rating in a suit-only (i.e. no disguise) challenge not by being silent but by running around and causing noise.
• Metal Gear:
  • In Metal Gear Solid, you can beat up guards and even shoot them in the back without causing them to sound the alarm. If you beat them unconscious or shoot them and hide before they see you, they will simply look around and then return to their patrol patterns as if nothing was amiss. Apparently being shot or beaten up isn't cause for alarm unless they see the person who did it.
  • In Metal Gear Solid 2: Sons of Liberty, the guards provide a fairly solid challenge without going to brutal measures to catch the player (difficulty dependent of course). However, patrolling guards, when not faced with a left turn, will always turn to the right, including when they are simply turning around. This effectively means that the player can stand next to a patrolling guard and not be seen, providing he always stands on the guard's left side. Also, you can shoot guards with tranquilizer guns, which mostly avert Instant Sedation except on Very Easy difficulty, but regardless of how long it takes, will cause the target to abruptly keel over with a grunt and start snoring. Other guards will find nothing unusual about this if they find a sleeping guard, and will simply kick them awake, even if they saw them keel over. This is particularly silly when you hit a guard who regularly sends status reports by radio (or interrupt a guard with a radio), and a group of armed soldiers come to investigate. After kicking him awake, one of the soldiers will radio back to report that there was nothing wrong before they leave. If they don't find the guard, they'll leave without doing anything about it.
  • Metal Gear suffers from this in both the MSX and NES versions. Sure, one can't expect a complicated AI all the way back then, but so long as you're not directly in their literal line of sight, enemies can't see you — even if you're standing just to the side, where you can literally run right past them or even attack them repeatedly without them reacting in any way, so long as it's a silenced firearm or with your fists. Not even other guards dying in their sight line makes them react. And when you do alert them, they just run in straight, grid-like lines spamming bullets in front of them with no real thought other than reaching you. The proper sequel, Metal Gear 2: Solid Snake, would give the guards a 45-degree cone of vision, more reactionary functionality, the ability to continue pursuit between screens (with non-alert guards maintained in the area even when off-screen), and be far more doggedly aggressive in taking you out.
  • Metal Gear: Ghost Babel suffers from similar AI, practically being a Spiritual Successor of the MSX games with elements from the first Solid title. The big difference is that enemies can face diagonally now, which means they can turn to see you at least, but all the problems from the original games still exist in the form of very narrow line of sight, probably literal on 'line', in whichever direction they face. Thus you can still literally run past them and brush shoulders even, so long as Snake's hitbox doesn't touch theirs or their invisible line.
• Thief: guards won't notice if their comrades are knocked out right on their side, they will assume that "just rats" turned off the lights, and other things. On the other hand, if they were really intelligent, the game wouldn't be playable.

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