What are some great open source games?

cross-posted from: https://programming.dev/post/3160775

I'm usually a fan of open source games but rarely do they manage to be actually great. People like giving recommendations like Super Tux Kart that haven't aged well and don't play well. What are some open source games that are legitimately good that I've missed?

My favorites are:

• Mindustry

• Sonic Robo Blast 2 Kart

• Powder Toy

• GZDoom (and all the amazing mods for it)

• Veloren (even though it's still in alpha)