Battlefleet Gothic Leviathan.
In a nutshell it is the naval combat spin-off game for Warhammer 40,000. Grim dark future, almost steampunk in style, about starships that look like gigantic Catholic cathedrals with plasma engines stuck on the back, and a ram bow nose cones, and giant guns stuck out the windows who fight living, alien starships with claws and tentacles called Tyranids. Also, there are Warhammer 40k space marines, specifically the Blood Angles and Flesh Terror chapters.
I've had the traditional table top game boxed set for a long time, but have never played it. I just don't have any interest in it from my friends, and I don't want to go to a game store and play with strangers.
Now I don't have to. This game I heard about months ago (and forgot about) was exactly what I was looking for. It is a 1-to-1 translation of the turn based table top game to IOS (and as of early September, also has Android as well). The game works well, and the phone handles all of the rules for you, so the battles play pretty fast, 20 minutes or less per match.
The game is only $5, way, way more cheap than the $50 you will pay for a boxed set board game that are out of print now. And it doesn't have any of the typical IOS phone game payment shenanigans like a cash shop, or pay to unlock crates to get more stuff. You pay the $5, you ge the full game.
I highly recommend it.
P.S. Don't confuse this game with BattleFleet Gothic Armada, which is a real time strategy game on PC.
If you want a fancy graphics RTS game, get Armada on PC. I you want traditional board game with no changes, get Leviathan.