Pay-what-you-want text adventure that runs in a browser and includes images, video and music. An amazing opening puzzle: build a world that can sustain life and evolve it into an intelligent space-faring civilization. Requires understanding and controlling dozens of variables to get it right. Daunting at first: you're basically given a reference book and told to have at it. But do the research, plan carefully, take notes, and it's all very rewarding when everything falls into place. Things get more traditional after that: explore a massive multi-level space station, get involved in political intrigue, rescue prisoners, build robots, a little sabotage...
It's easy to bounce off the crazy amounts of alien-sounding people, places and concepts, the high difficulty (no in-built hints and no walkthrough), the complex map (2/3 of rooms are purely decorative), but it's worth persisting for the thoroughly implemented world, the challenging but fair plot-integrated puzzles, and the twisting, turning story in the grand tradition of "golden age" sci-fi.