Pathfinding... yeah... we had lot's of troubles form getting the bot's through the door and off the leader in HL engine
But still... in strategic games if you are much stronger and offer them an alliance (in strategy games such as Civilisation, Alpha Centauri or Space empires) but they refuse to sign it because you already violated the alliance. mmmkey.... "please sign it i want to cooperate with you. i dont' want to be at war anymore. if we sign we will both benefit". and then they say no. i say ok suit your self - they get nuked! why is that so? why they don't want to ally with much stronger opponent? why do they not beg for mercy? why do they oppose you eventhought it is a lost cause and eventhough this time your intentions are really true.
Remember those late starts in Civ where you had single city with phalanx in year 1900 while you already had nukes and armour. and they decided to oppose you even after warning and beggin to sign for peace.
Or in Space empires where i deliberatelly (personal project) gave my self certain advantage and ebcause of that everyone wanted war with me. i said ok and destroyed their suns (not enough of them, battle still lasted on) but most races got erase evethought my intetnion was to end game with certian years of peace elapsed or with points from colonies (we all started with same colony tech and same amount of them at start). they are rather erased then surrender. no (human) logic at all.
Esepcially in CIV where you can win by launchin a space ship.