> why isn't there a Super Awesome Open Source Game Engine that's the heart of all 3D games?
Unreal is the closest thing, but there's still lots of new/strange/innovative stuff going on in rendering, which means that lots of bits are hard to reuse. Rage, for instance, has a pretty nifty virtual-memory for textures scheme, which no one else has really done.
Also, licencing costs. Why pay a rival company money when you can create your own engine in-house? Unreal has various licencing agreements, from (probably) 8 figures for an unlimited license down to 99$ + 25% of any revenue above $50k per title (and anywhere in between).
In particular I'm thinking of Criterion's Renderware engine. Originally funded by Canon it was very popular. Then Criterion was sold to EA and everyone dropped it.
> Also, licencing costs. Why pay a rival company money when you can create your own engine in-house?
Because developing a AAA engine from scratch is a multi-million dollar enterprise at this point.
You actually need to develop your system faster than the leading edge so you can catch up. That's an expensive ask. Most companies arrive, after 2-5 years, with something that was as good as UDK or idTech n was ... years ago.
Paying the $500,000 or x% of revenues is often the fastest, cheapest way to get your game out.
Unreal is the closest thing, but there's still lots of new/strange/innovative stuff going on in rendering, which means that lots of bits are hard to reuse. Rage, for instance, has a pretty nifty virtual-memory for textures scheme, which no one else has really done.