It's not Open Source, but you do get the engine and all the source for free. It's built on technology from CryEngine, Double Helix, AWS, Twitch, with a significant number of bugfixes, improvements, and features.
I'm genuinely excited to see where it goes, but, in full disclosure, I work for Amazon Games Studios (though not on Lumberyard).
"Q. Is Lumberyard “open source”?
No. We make the source code available to enable you to fully customize your game, but your rights are limited by the Lumberyard Service Terms. For example, you may not publicly release the Lumberyard engine source code, or use it to release your own game engine."
There's also Lumberyard, Amazon's new entry into the game engine market: https://aws.amazon.com/lumberyard/
It's not Open Source, but you do get the engine and all the source for free. It's built on technology from CryEngine, Double Helix, AWS, Twitch, with a significant number of bugfixes, improvements, and features.
I'm genuinely excited to see where it goes, but, in full disclosure, I work for Amazon Games Studios (though not on Lumberyard).