This engine is very interesting. I had seen it sometime back but seeing it on Steam is what made me really look at it. You can run the editor on Windows, Mac or Linux. The whole thing is BSD Licensed (or MIT) editor, engine and all. It is C++ code and features their own custom scripting language that is somewhat Python-like and influenced no doubt by other scripting languages. Also did I mention it publishes to Android, iOS, Mac, Windows, Linux and even HTML5, and you can also grab the binaries off their side (20 MB ~) or source from GitHub. Neat project. Still havent had the joy of making anything great with it yet. Oh and it does either 2D or 3D.
From what I read they used to use it for private use, so they would have clients and make games for them and they decided to open source it in the end.
I remember when they first released it as free software, it's come a long way since then. It's remarkable to see how much traction they've gotten. Bravo!
It's just a hobby game, I doubt I'll do anything other than open-source it, but it's been fun. I don't have any experience with other engines, but this one has been great to learn on. The GDScript isn't too hard to figure out, but their documentation can be a bit lacking at times. It feels really polished for an OS project.
I haven't used any other engines so I don't have any experience, but I would still recommend this for a beginner.
I've just started using Godot to create a hobby game too!
GDScript is very nice and simple and the guide is quite good but I definitely agree with you that the docs are fairly sparse, especially the API and class reference.
I've dabbled with Cocos2d-x in the past and am thoroughly impressed by the polish of Godot and so far have found it more approachable. The demo projects are also very full featured.
It's MIT Licensed, you could take the project compile it, and put a price tag on it as a tool, and it would be legal. You could make a game that makes you millions of dollars and not owe a penny to the developers. You would be considered many nasty things probably, but legally speaking the MIT License would not forbid you doing that. You could also always contribute back. The restrictions of Unity are not the restrictions of Godot. You can make the millions you want to, you can redo the whole engine / tooling however you see fit. Just keep the original copyright notice and remember you have no warranty any of it works basically.
I know a lot of indie game developers that use Unity, and not having access to the source code to understand why something isn't working as expected is a very common complaint. Being able to dive into the code you're building on top of is a super power.
AFAIK, Unity-the-engine still has a vsync bug edit: on Linux that makes running unity games on my laptop burn one of my CPUs at 100% nonstop. It heats the thing up, burns precious battery life, and is doubly infuriating if you're playing a game that should be light on resources, like TIS-100.
This has been an issue for years, and they can't be bothered to fix it.
edit: the reason is obviously that Linux is a small customer base, and you'd only notice this on Linux laptops, which is an even smaller subset. However, for indy developers in niche genres (where in some cases, like TIS-100 for example, you can expect a more significant chunk of Linux users), I think the fact that Linux support supposedly comes for free is one of the reasons to use Unity, making this doubly cynical.
UE4 is massive and overkill for 2D games or low-poly 3D, especially if you intend to release on mobile (which Godot is designed to do well). It really depends on what you are trying to do.
Looks like Godot is OpenGL-only, while Unity can also target DirectX up to version 12. That might be a problem if you're targeting XBox, but it's likely not a problem otherwise.
It's a cool engine. I hope they will integrate AR capabilities some day (there's an open issue about this on GH). Maybe they could integrate with ARToolkit once v6 is released. Since all I do with game engines is AR my best option so far is Unity (sometimes with ARToolkit, sometimes with Vuforia)...which is good but not great. I'd actually love to switch over to an all open stack.
Hopefully the C# support in v3 will be good to lure some Unity devs over :)