tl;dr it's a strategy game, kinda like Stellaris (but... dumbed down?), it's free (for now) and fully playable with Proton Experimental, I have enjoyed playing it.

Stellaris Nexus, dubbed by devs as Stellaris experience under an hour.
If you love Stellaris or strategy games in general then I would recommend trying this one, there is a week of playtest (after which it will release as beta/pre-release, dunno the cost).

There is a lot to be polished (especially UI-wise) but I definitely do not regret sinking the last hour into first play-through of the Succession game-mode.