Now it's our turn to give back. As of 5/11/10, Aquaria, Gish, Lugaru HD, and Penumbra Overture pledge to go open source. We are preparing the sources right now and will be releasing them ASAP. We spent last night preparing Lugaru and it is available now. The code is still a little rough (no Visual Studio project yet, for instance) but hopefully with the help of the community we can rapidly make it more accessible to everyone.
Link to Original Source