A while back I mentioned the Humble Indy Bundle, which was a set of 5 or 6 downloadable computer games. Very cool little titles, of which the cream of the crop is a beautiful game called Aquaria. My wife and I have logged a lot of time playing Aquaria. It's one of very few computer games I've ever felt the compulsion to truly play all the way through. After about 50 hours of play, we not only reached the end but also amassed nearly all the in-game achievements.
Then we broke out all the mods we could find for the game. Most of them were pretty short, though, so Sarah and I decided we'd take a stab at modding it ourselves.
Our mod is called Feral Beast. What's available from that download is just a preview; enough to keep you busy playing for an hour or so. The mysterious beginings of the story, and the first 5 map levels we got finished. There's a few hints towards the eventual plotline, but it's mainly just an exploration mod at the moment. Poke around with it and have some fun. You'll need Aquaria to play, of course. You should carefully read the installation section of the readme.txt file included in the download, as the new recipes don't install automatically, and must be manually placed inside the game folders.
Additional chapters will be added as we create them. The actual level editing stuff is fast and easy, but there's some significant time investment in designing new creatures and coding anything particularly interesting, so it'll be a few weeks before you see an update.