Source code is available now! http://infiniteammo.ca/blog/aquaria-source-released/
The Steam UI beta could, briefly, assign games to multiple categories.
I spent an hour or so assigning all my games: TODO, First Person Shooters,
Finished, Worth Playing, Indie, etc. It satisfied some deep OCD in me or
Shortly before the beta ended, this functionality was removed...games could
be assigned to categories you define, but only one at a time. There's
probably a good reason for this change, but I don't understand it. Most
games defy simple categorization.
Some blanket categories are built it ("Mac Games", "Favorites", "Recently
Played"), but it's not the way I think about my games, and the way I want
to find them on a whim.
So I built a tool to solve this. http://steamtags.icculus.org/
Basically, you go there, you tag your games, and then you can filter them
by those tags. Click the game to launch Steam and install/play the game.
Tags follow you from computer to computer. It's that simple.