I'm guessing Gavan would like to protect his work a bit and not just give out licences to do anything you want with it - if others want to commercialise, he should get a fair cut, otherwise it's going to be a hard sell to investors. IMO that's completely understandable. I find it sad that things like non permissive CC licenses are regarded as so bad in the open source community - making a project like this completely open is very hard to do as a full time job because of that.

I will put it up on github soon :) License requires a game key for now, but will be open sourced eventually if I can afford to do so. (see other comment on open source)

Full source will be distributed with every game key, similar to licensing the Source SDK from Valve, but that is API-only IIRC. I would really, truly love to open source the whole thing but have to pay the bills for now. I think I will open source it if possible once I have made enough money to survive a few years (If I even get to that point!).

No royalties or fees are charged.

I also consider any licensing deal offered to me with pretty loose restrictions (and I have had two bigger requests in this regard so far).

If/when I get to the point of opensourcing, it will be a very permissive license - like ZLib or MIT.

I'd like to know that too. Right now, I think the engine looks more interesting than the game -- but the engine is really only interesting in as much as I can play with it...

C++, OpenGL, JSON is used for data storage, but not strict JSON (I allow comments and may add a few other features).