This is a portable battery powered Rogue-like video game- The dungeons of Doom. The game runs on Atmega32 microcontroller. So it can be plugged to any TV set with NTSC decoder.
AVR to TV interfacing is done with well known video DAC made of 3 resistors and is tuned to 75Ω TV input resistance. The whole project including 9V battery fits in a box for Altoid mints. Project source code can be downloaded here. Game code is far not complete, like only one monster implemented, also player inventory has no different weapons and items. But I guess there is still some fun to se some action on TV screen.