There are a few that are really fun. My kids were getting interested in gaming, so I had to have a look into suitable games. So here is a kid-friendly list of great stuff that runs natively:

GCompris: A lot of nice learning mini games for the very young (also good to teach e.g. usage of mouse and keyboard)

Minetest: Very similar to Minecraft, but with its own twist. Highly customizable with mods and completely free and open. I am running my own minetest server with a customized non-survival world that is used by my family.

Widelands: A really great community adaption (and extension) of the Settlers II. My son totally loves it.

Unciv: Civilization game based on the Civ5 ruleset. I actually had to deinstall it again on my mobile phone (also available for Android) because it has the same addictive properties as the original…

And for non-free games: Lutris + GOG makes me happy. Currently playing some older Tomb Raider game. Although not really native, I think. Probably using Wine or so…