Umm, there's so MANY, solitaire, chess, spider-solitaire, warcraft, PVZ, etc.
Seriously, we can't determined what games that can be played with 256mb graphic card without knowing it's specs...
Dude, you're way behind time!! We're talking Mario brothers on enthusiast settings on a 256 mb card!
To the OP:
On a more serious note, kindly put up the complete specs of your rig. CPU, GPU, RAM, Resolution, what 'kind' of games, etc! There are so many factors to be taken into account to answer that question.