Return To Ringworld was a 1994 adventure game released for PC, based on Larry Niven's Ringworld. The game wasn't well-received, with reviewers blaming inconsistent difficulty and trial-and-error puzzles as the main problems. It did have one hidden treasure though -- a fully-developed card game called Outpost Alpha that, arguably, was the best part of the whole thing.
Outpost Alpha was accessible from an in-game terminal right from the start. The player is pitted against three opponents, the goal to build your outpost first. To do so, you must place a "platform" card on one of the eight sections of your station. Then you can build a department on top of it.
Players can foil the construction efforts of others by playing hazard cards that make you miss your turn or prevent you from building unless you find the appropriate cure. This made the game fairly luck based, with most of the skill coming down to picking the right card to discard on your turn. Each department also protected you from a particular hazard, so the better you do, the harder it is to be obstructed.
It looks simple, but I played the hell out of Outpost Alpha. I guess that says a lot about Return To Ringworld.
Many years ago, I started coding a modern-day port in .NET, using nothing but screenshots of the individual cards. I got about a third of the way through when I realised the folly of my activities -- there's no way I could release it legally.
Potentially, it could be finished as a free labour of love, but I'm a bit busy these days making commercial titles to work on it. One day I'll find the time...