Today I heard about Amazon releasing a game engine known as Lumberyard, which is really just an offshoot of Cryengine. The license is interesting – it gives full access to the source code for free. Unreal Engine 4 has a similar license, which allows access to the full UE4 source code.
Thing is, despite both engines allowing full access to source code, they aren’t really open source software. Unreal has a weird bit of its license that says you can’t use any source code from the editor components in the game itself. This seems to be to prevent someone from creating a standalone editor for users without needing them to accept Epic’s licensing terms. Both engines restrict who you can redistribute source code to (only others who have also accepted the license).
The bigger tradeoff between their licenses, however, is how each engine makes money. Lumberyard has zero royalties, but if you want to use a cloud service to host game servers you are required to use Amazon AWS (though they have an exception if you want to use your own hardware). Unreal has no such stipulations, but Epic does require a 5% royalty on gross profit (removing that royalty requires a special and very expensive license from Epic Games).
The biggest problem I see with Lumberyard versus Unreal Engine is that Lumberyard doesn’t seem to have a way for the community to participate in its development. That’s a huge part of OSS, and while Unreal isn’t OSS it does get the closest I’ve seen for a piece of commercial software: Once you have accepted Epic’s license terms, you can get access to the Unreal Engine github project where the community can and does submit patches to the engine itself all the time.
Despite the offhand use of “open source software” as a label for UE4 and Lumberyard on forums (see: reddit), they are both definitely not in the spirit of open source, though that certainly won’t prevent me from using them. If anything, what’s going to prevent me from using Lumberyard is the fact that right now it’s pretty much just Cryengine under a different license, and usability of Cryengine leaves something to be desired. I’ll probably be sticking with Unreal for the time being.