I tend to find
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a much better option than UE4 or Unity (unless you want to make use of their asset stores). It is very light weight, easy to build from source if you need to, the code base is super clean and easy to navigate (something that is very rare for big mature C++ projects). The built-in editors provide basically everything you'll need from code editing, scene layout, debugging, etc. It defaults to using it's own scripting language GDScript, which is basically Python if it were made with game development in mind. Though it also has built-in support for a visual scripting setup. (Though it's mostly meant for rapid prototyping ideas you want to test out, not particularly useful for a finished game. If you use it you'd want to replace parts with proper code as you go along.) There's also external support for C# and a few other languages. You could also always drop down into C++, either directly editing the source itself, or developing plugins or modules for what you need.
It's totally free and under an MIT-style open source license, which basically means you just have to keep attribution in place on any engine files you redistribute. You are free to license the rest of your files/assets to whatever works best for you. Plus worth noting, this has dedicated features for both 2D and 3D right from the start, you can use either or both. The 2D side is rock solid and feature rich, the 3D side recently got a big overhaul to update its back-end to use a more modern asset pipeline for physically based rendering (PBR) and the like. It has pretty good compatibility with Blender and that's going to get even better later this year. One of their current Google Summer of Code projects is to provide a better export plugin for Blender that does away with the need for an intermediary format like Collada/FBX and directly exports to Godot's native formats. Plus Blender 2.8 will be bringing in additional features to make it easier for game engine devs to more tightly integrate with Blender in their pipelines and from what I hear the Godot devs in particular have been in regular talks with the Blender devs over this.
It has a smaller community around it than Unity or UE4, but that community is very active and helpful. They're constantly improving the documentation and there are a fair few folks out there producing tutorial content for it. Here are some worthwhile ones to get people started:
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(This is mainly for the older 2.x, but there is still a lot of useful/relevant tutorials here.)
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(Mostly 2D related content.)
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(This guy has 3 nice beginner friendly tutorial series for Godot 3 that focus on the 3D side of things.)
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(His Godot stuff is mostly related to 3D and should be for Godot 3. He also has some decent Blender tutorials, as well as some for a few other engines as well.)
If you need help, it would be worthwhile getting involved with one or more of the several communities surrounding it that works best for you:
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