Galactic Junk League [official site] is a free-to-play multiplayer spaceship combat game where players can build and fly their own heavily-armed megatoilet. If you're not even remotely interested in that, sheesh, move on. I suppose you could also build an X-Wing, Viper, or imaginary spaceship of your own design but the tools let you build a toilet or fish or mug so? Anyway, having made your own ship with different weapons and abilities and whatnot, pew pew off you go into battle. Galactic Junk League is soon on Steam Early Access soon so let's have a look in this trailer:
Yeah, I reckon I'm up for that.
It's not a serious sim, obviously, rather a loosely class-based shooter with a heap of customisation. Players start with only their ship's core, which must be protected or it's ttfn, then slap on hull blocks, armour, weapons, modules with abilities from shields to jumps, weapons, engines, maneuverability modules, decorative bits, and so on. Zippy ships! Tanky ships! Ships bristling with guns! Parts consume points, obvs, so a full-size Death Star might be off the table but a fun-size one might work. Check out this ship-building vid for more on that.
Then off they fly into battle for 5v5 action! Control is WASD for movement, clicking for shooting, then number keys for special abilities. Pew pew!
I've had a quick poke into the beta and it looks like monetisation comes from selling things like XP boosters, pieces with different skins, and big bundles of bits otherwise earnable by playing. I've not played enough to get a sense of how intrusive that is, mind.