O2EM is an Odyssey2/Videopac emulator originally written for PC with Allegro library. I've ported the game to Nintendo DS & SDL.
You can play it provided you have a R4/M3/AceKard or whatever for your DS (Slot 1)
- game selection with a text but convenient menu
- good speed (not 100% but close)
- be careful: you have to put UFO.bin in the roms directory alongside with the BIOS file. You'll find both files on the WWW, just google odyssey roms
- source code available. To recompile, follow instructions from here.