Wrote a mini adventure game in BASIC for the ZX-81. Since it only had 1K of RAM, each room in the game had to be a separate program (max around 25 lines of code or so), and at the end of the room, depending on what actions you took, it asked you to wind the cassette tape to a specific location to load a new room. When I could finally afford the 16K RAM pack, I rewrote it as a single application. Couldn't believe how nice it was to have that much memory.