I wrote a Zork-style text game in high school as an end-of-year project on a TRS80 model III, using its built-in BASIC. There were three stages of the game, and all was going well until I ran out of RAM. :( Stage 1 was complete, though. For being an elective, I put a lot of work into that game. The teacher even let me lug the giant beast home once or twice.