After seeing @Storm's awesome game recommendations (thanks for recommending Kingdom Rush Origins) and being inspired by them, I thought I'd recommend a game myself. And I picked my all time favourite, Armello.
So the main point of this game is that the (mad) king has been corrupted by an ancient dark force called the Rot. And what you have to do is to be the first to become the next king of Armello. Now this can be done in four ways, Prestige (have the most prestige when the king dies), kingslayer (kill the king in battle), Rot (same conditions as kingslayer but have more Rot than the king) and Spirit Stone (collect 4 spirit stones and cleanse the king of his Rot by touching him).
This is a game of chance, and a short game, but it can be replayed infinitely because it has a randomly generated map. The AI characters (and Players) will not take it easy on you, so you would have to be on your toes.
This game doesn't have native Linux support, however, you can play this on Linux using Proton. This USED to have native Linux support, but I think the devs have removed it.
Check it out here: