This comment comes up often in the gaming community. My guess: they've done the math and the business gains do not outweigh the inputs. Between the codebase sanitation and the licensing issues with third-party products, that would be a pretty massive headache. There's the intellectual property argument to make as well.
For modding specifically, that also dictates how your game is built and requires extra work to do it right. Not every game needs it. The reality also is that it's easier to sell people games on a shorter cycle when the previous one doesn't have legs. I imagine the vast majority of the gaming population don't think twice about modability - they're happy playing a focused game and eventually leaving it behind.
To be honest I'm not sure that the game engines market isn't already saturated, raising the bar even further for a big AAA newcomer.
Like others have said it isn't just about 'opening your engine' and leaving it at that. All of a sudden you have to polish up your editor for external consumption (ooops.... the editor is crashing on this PC config that we've never had in the office?), write documentation and tutorials, putting out really good examples, engaging with this new type of community, etc.
Is there honestly room in the market for an engine without a clear niche these days? I mean you seem to have Unity and UE4 at the top tiers, then engines carving out a niche (Godot comes to mind), your lower-level stuff (how's OGRE doing these days?). There's a few random ones on Steam even (Leadwerks, GameMaker Studio, RPG Maker, etc) for other use-cases.
I think of CryEngine 3 -- that's the most recent move by a big player into the engines-for-everyone space. How is it doing these days? My impression is that it's struggling to get mindshare, but it has been awhile since I've looked. I'd be wary of bringing a new engine into the space after watching how that's going for them.
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."
That's a fair point. However, they could still opensource their engine, which would provide them with some pretty major benefits: How likely is it that Doom would still have an active community if it only ran on DOS, with no improvements?
Licensing is hard. Open Sourcing is easier. Although codebase sanitation is still a massive issue.
>For modding specifically, that also dictates how your game is built and requires extra work to do it right.
That's not actually true. If opensource the engine code, then people can probably figure out a way. Heck, if they're dedicated enough, they'll do it even if you don't opensource the engine. See Minecraft.
For modding specifically, that also dictates how your game is built and requires extra work to do it right. Not every game needs it. The reality also is that it's easier to sell people games on a shorter cycle when the previous one doesn't have legs. I imagine the vast majority of the gaming population don't think twice about modability - they're happy playing a focused game and eventually leaving it behind.