Of course 30 years ago there was "1K Chess" for the Sinclair ZX81 (Timex/Sinclair 1000 for US readers) - which, despite the name, was actually just 672 bytes of code. (The program had to run in a machine with 1K of memory _total_, which obviously included space for the machine's workspace and display file - itself ingeniously optimised to only occupy memory space for parts of the screen that had been printed on.)