Doom for PocketStation.

Doom has been ported to everything between the sky and the ocean and now it's even on the Pocketstation!, whats even more insane is that this port supports making your own WAD maps.

Official site: http://www1.atwiki.jp/pocketstation/pages/196.html
and the Doom Pocketstation wiki.
Download Doom from any of the mirrors here: doompocketstation.zip and then theres 2 ways of transfering this to your Pocketstation:

1) Use the Ps3 memory card adapter and transfer Doom over using MCRWwin.exe which you can download here: http://www.geocities.jp/altshibabou/win/MCRWwin.html

2) Connect your Pocketstation to your Psx and burn a disc with this program+doom on it: http://onorisoft.info/psx/tools.htm (requires a modded psx)

And if you don't have a Pocketstation then you can try the Pocketstation emu pk201_090909.zip .