If you think PC games these days would come on nothing less than
a CDROM (heck, even those game demos weigh around 100 megs
already), check out .kkrieger,
a Doom 3 like game that is only 96kb (that's
kilobytes or 0.096 0.093 megabytes, folks). You
can fit about 15 of those on a floppy disk). It's written totally
in Visual C++ and x86 Assembler. Requires DirectX 9.0 and a rather
high end graphics card with pixelshaders (e.g. GeForce4 Ti or ATI
Radeon 9600) to run.