I have played the ever-living heck out of this game on subway rides. It's been a couple years since I last booted it, but it's a great timekiller in the sense that it still piques my imagination while not requiring me to think too hard.

The sequel "Beyond the Chiron Gate" adds more complexity to the formula, but is still fundamentally a similar game.

https://spacegoblingames.itch.io/beyond-the-chiron-gate