I'd suggest to build a game on Roblox. It's easily accessible through Roblox Studio, it's well documented, it has a young and welcoming community, and it teaches you a lot about client-server architecture. Plus, it comes with tons of freely available assets, you can invite others to work collaboratively, and you can publish your work and get some feedback from friends and family. I feel like Lua is kind of an exotic programming language but it works well in this environment.
