[dudeinhawaii]

It might be somewhat related but Unity and Monogame target very different developer experiences. Monogame is an alternative to low level frameworks like SDL/SFML/etc for C++. It's not a game engine.

The difference is that you get to code most of the engine as opposed to mostly coding gameplay. That's of course a significant trade-off. If you like being low level and understanding how things work and learning a ton then Monogame is the tool to use. If you strictly want to make a game and don't mind ramping on someone else's toolset to "go slow to go fast later" then Unity/Unreal/Godot are the tools.

Monogame shines when it comes to 2D games since 2D games require less specialized engine tools and most of the editors can be made quite easily for a 2D game and will teach you a lot. Don't get me wrong, it's capable of 3D but the experience will be much harder and unstable. You'll be much more at the mercy of outdated open source libraries for things like importing animations from your favorite 3D editor. Conversely, writing a library to import and load your own 2D animations can be done in an afternoon.

The showcase of games built in Monogame echo this with lots of heavy hitters and well-known 2D games and very few well-known 3D games.