Shadow Empire is out on Steam:
https://store.steampowered.com/app/1154840/Shadow_Empire/
What is Shadow Empire? As a owner of the non-steam version of the game, I can say I've never seen a game quite like it.
Long story short there was once a galactic empire, then the apocalypse happened on all worlds, and civilization collapsed, and now you have to rebuild/conquer it. Start from the beginning with infantry and mad-max level tech, to tanks, mechs, nuclear missile launchers and more.
The game can generate a massive variety of planets for you to play on each with it's own different challenges. You can play on a desolate, airless moon, a Dune-like planet with gigantic worms, a frozen planet, or a rare-Earth like planet. The airless moon may have you scrounging for resources, while the dune planet's worms may destroy your military quite easily. The frozen planet may have a breathable atmosphere, but alien toxic life that has its own difficulties. The Earth-like planet may look easy-mode, but it's actually one of the harder ones as giant dinosaurs/other horrific monsters jump out at you from the forests and jungles to ambush you. There might be huge ruins for you to discover lost tech, if you don't get ambushed by armies hiding in the ruins. This is only the surface of the crazy amount of playstyles and planets, each demanding its own strategy.
This game simulates detailed logistics-you'll need to support your troops with supply lines and resources. Run out of ammo and your armies will get crushed, running out of fuel for tanks and the like also has similar effects. I once lost a game because I fielded a army of heavy tanks, which dominated the battlefield, but took about 1500 oil to move 3-4 tiles and a similar amount of ammo, bankrupting my empire and losing the war.
There a also a complicated economy system, where you need to balance your private economy with the buildings you build-try the civilization city spam tactic and you could find your empire collapsing due lack of income and people to man the buildings.
The game sports a 350 page manual that you can read online for free to see if you like the game mechanics:
https://www.matrixgames.com/amazon/PDF/SE/Shadow_Empire_manual_EBOOK.pdf
DasTactic has a slightly outdated guide here:
https://www.youtube.com/watch?v=BivVweJ5-iA
Word of warning: this game is hard, even on easy, as the AI is really good