Ok, so a lot of kids today say minecraft is the most multiplatform game ever, but I think it's Doom
Like, DOOM is on fucking EVERYTHING.
Amiga , IBM PC, BeOs Acorn, macos, GNU/Linux, DOS, windows, all the modern systems, the DS and the Wii, SNES, 64, all MS and sony consoles, ipods, cell phones, mobile OSes, sony ericcson, the fucking zune, the Nspire, web browsers, they even have it running on rockbox, and even hospital monitoring PCs
And the maddening thing is that I KNOW I've missed a few.