Level 9's text adventure games (today probably known as interactive fiction) were amazingly good. Their best was probably Snowball. You really had to understand how the ship worked, or you'd never get anywhere (you could "go" to something like 10 million rooms, almost all of them totally uninteresting). The plot was good, there was sufficient humour to make things interesting (the hypodermic-wielding robots were called "Nightingales", but weren't angels of mercy, and I won't go into the roboticised form-filling to get the welder), and the coding was tight (not that I ever tried to cheat on the game).

I never finished it. Shame, really.