Circa 1992
A Columns clone in 68000 assembly, for the Atari ST.
My initial intent was to fit it into the bootsector of a floppy disk (without any compression), but I overran the 450 or so free bytes I would have in the bootsector. I therefore ended up adding a bunch of text, graphics, and sound effects; and intentionally overran the limit even further (I went up to a whopping 1832 bytes).
The code could still run from the bootsector with a bit of cheating: I was storing the overrun in the FAT backup and therefore keeping the disk operational until a write operation on the disk would overwrite the FAT backup and screw up the game.
Video (A little choppy due to the sluggish video capture of the emulator)