Yes. Donations. Ads. Merchandising. Sponsors.
E.g. jquery, Wikipedia, Google, Facebook, Angry Birds. They're not rich, but they make enough to pay themselves industry level wages.
IMO, donations make about as much money as normal pay to play games. Sometimes more. Choosing not to pirate your game is in itself a donation. Except charging people for things will be much more lucrative when they don't know how to pirate things (i.e. Microsoft).
(heheh, put food on the tablet)
Very bad examples:
- Wikipedia is pure sharing and have the same benefits for everybody than jquery, even more.
- Google and Facebook are not open source. Their core tech is not open source. They have some parts that are open source (only recently for Facebook but they had the mentality anyway) and it's a win-win because it's all tools and support. Google sell information-based services and advertising, Facebook sell information and advertisement on graphs of people related in some ways, so it's specific job far from video game.
- As far as I know, Angry Bird is not itself open source, only techs used in are. Also, it have been made open source only far after it's success.
Let's take Aquaria as a better example. It benefited from getting open source, but it was after it was already successful.
That's the problem of open source projects: you have to prove your project is interesting already without being open source, then people will get interested, and at some point some might be wanting to help make it evolve.
That don't explain how to get money from open source games, but it points that if at some point in the life of a game with a community you make the code open source, then the community will care and make it a bit more successful.
If you make it successful from the start, prepare to sell service.
The best example I can think of would be an online game where the client is open source, but the server is not. You provide ways for other to build custom servers, just basic protocols for example, but say you provide a massive server that is central to every online play?
If you sell both the client and access to this special server, it might work.
You can invent other variants of that.
The point is to make an interesting service to your "users" to make them want you to continue. That's why there are open source foundations: for companies and people to pay other people to make a product continue to evolve.
Personally I don't see any other way than selling service, whatever that means, but I suppose that the technologies and mentalities might change in the coming years which makes the game change widely and create new selling models that don't rely on information retention. I don't know what obviously.
I often think and explore the problem because I'm working on a game that have to be closed source to be sold but I think it would be far more successful if it was open source (because part of it's fun is based on "variety" of some type of content). But I can't see how to do that and make a living, from my current starting point.
Also, BorisTheBrave is totally right.
If you make your game open source, it don't mean people have the right to do something public with it, in particular most licences don't allow to make commercial use of the code. However it helps a lot to clone, obviously, which can be a problem if you are successful but not rich early enough to just ignore the threat.
Or you have to be very niche, which makes your game very unlikely to be cloned by people just wanting MUUUNNEEEEYYYY, as they will more target short and "popular" games.