The 16 Bit Arena website has word that their promised experiment is underway to see if this multiplayer came can be supported by free downloads and donations. The game is offered free on most digital distributors, and they are offering free direct downloads from their website with no signups required. Here's word:

FREE PROMOTIONAL GIVEAWAY IN ALL STORES MAY 16-31! Tell your friends so they can get their free copy and join with you! All stores in the Buy section should have it free by the end of day May 16, but in case you'd like to skip signing up on a store's website to download it, here's a direct link. (Note: Downloading from Desura may currently have some media installation issues that are also resolved if installing from this link.)

If we get enough people (filling even one server completely with 9v9s), we'll be experimenting with something new. We'll open up donations, and every $5 you send will put you in a drawing to get a character made just for you! And if this is successful enough, we'll keep the game free permanently and do the drawing on a regular basis. If you don't win, 10% of everything sent will still go to ChildFund (supports hungry children around the world), so either way somebody wins.