Cory D. at BoingBoing drops this video of the $100 OLPC running Doom on its reflective dual screen. Ghetto, but man, I remember wishing my old TFT screened laptops would play doom this well. Doom shall be distributed to the poor!
Oooh, frame rate lousy, even with that reduced screen size - unless it was running at the OLPC's standard 800 by 600 colour resolution, which is possible. In that case, a version that ran at good old 320 by whatever would probably give you a nice playable game.
And, if not, there's always NetHack.