I also have my own game engine, if you're happy with 2D retro pixelart graphics (polygon support and 3D comes after I move some of the rendering away from the CPU to the GPU). It also has software synths, if you want adaptive soundtracks.
Having more features, especially those aimed at corporations instead of indies, means it's harder to figure out how to make simple things work, especially without tutorials. Even the things that could be simple are probably still more complicated than an indie engine in order to help large developers do what they need to. Since Unreal Engine is pretty much designed for Epic to make their games in, you can bet that that's their first priority, and indies get table scraps.
The flip side of that coin is that you have access to a lot of the features that the corporations do if you want to put in the time to use them.
My list has a few things that aren't listed in that GFS link, which might be useful for the more specific indie types (Solarus, OHR, OpenMW)
Stride does look like a very good alternative if the intent is a 3D game and C# programming, so possibly the best case for Unity veterans in that regard.