Noctis... it's just... wow... just look at this screenshot:

This is just an amazing program. Space exploration, you can travel to star systems, land on planets, take pictures, panoramas, write notes, and submit the information to a central server for storage so that everyone else has the information you recorded. Infinite universe. Download under 1 megabyte. No violence (Foomer say woohoo!), and to top it all off, you get to play as a cat! Of course, you can't see yourself, and probably can't see other people, but that's beside the point. The only real drawback is the lack of interaction with other people (you can see their space ships, but you can't do anything about it), and the low resolution of 320x200 (Gasp!). But, despite the flaws, this is a great game (if you can call it that).
Oh, and a few more details. This guy is really into it. He describes things to the minute details, including showing the alphabet of the race you play as, and the fact that they use a base 5 counting system. It's amazing.