I've recently started learning Godot Engine and am having a great time with it. It is so lightweight and simple to jump into. I find its interface very intuitive and as someone just tinkering around for fun, it doesn't demand a huge investment of my free time to learn it. GDScript is more than sufficient for me. As someone who typically does Pico-8 stuff for fun, the Python/Lua-esque syntax of GDScript gets the job done.
A friend of mine is building a framework for Unity that allows for easy multiplayer. I haven’t tried it because I don’t work on games but it seems like a cool idea.