Think of the 128 bytes RAM to be only used for your dynamic gameplay state variables. C64 (and other home computer) games had to load all code and data into RA

Think of the 128 bytes RAM to be only used for your dynamic gameplay state variables. C64 (and other home computer) games had to load all code and data into RAM, which usually accounts for most RAM usage. Game consoles like the Atari 2600 stored the code and static data in a ROM cartridge. For simple arcade-style games (like Pacman), 128 bytes of RAM is more then enough to manage the gameplay state. (still of course: a chess engine in 4 KByte ROM and 128 bytes RAM is pretty damn impressive)