Same thing is impossible neither with Quake engines and all its derivates, due to orrible GPL license, nor with id1qc. You can make even a commercial game, sure. But forget abou keep your engine code/gamecode modifications for your own. And forget about merging with closed source apps (is GPL violation iirc).
Unity same story: closed source engine (only binaries), gives less game code bundled in C#/Js but has a huge wiki with tons of code free of use without posting any modications at public.
So what's open source, what's freedom? The liberty to make your own business with some limitations or the obligation to make your ideas free?

Just to derail this conversation a little on topic:
Why, Electro, don't you post some in-production shots? I don't know, a 3d app video of a game environment prop during modeling, a debug view of the game, some photos of you guys discussing game processes during brainstorming, stuff like that because people like that! I know it's a lot of extra work to do (and maybe you guys are already exhausted!


Put beforehand that I think that work MUST be payed an complex intellectual work (any kind) MUST be payed MORE, DOT, another thing is if the sentence was put in this way:
"Hey Electro, cool stuff you're doing! I have an idea that maybe could help you guys to reach you kickstarter goal faster: why don't you put in the introduction, that, after (I dunno) 2 years of game shipping, engine source code will be released under a permissive open source license to thank all our fans that help us for our big work with a big gift for the community!".
Imho a sentence like this is another pair of shoes and maybe this endless conversation would have been focused on more Reflex game matter
