HighFleet is hard, but here's a good reason for it. Once you really get into the atmosphere, you'll stop caring about that.
Aside from some doubts about the balance and the AI, and some Warhammer-specific quibbles, Warhammer 40,000: Battlesector is a great Blood Angels experience.
Legend of Keepers is a fairly engrossing game with a simple yet fun gameplay loop and glorious gory pixelart.
Endzone: A World Apart shows a much more conventional post-apocalyptic world than Frostpunk, and is also a much more conventional game.
Per Aspera reaches for lofty heights, but I could never shake the impression that the difficulties I encountered were more because of the game breaking down rather than Mars being a hostile place. But who knows, patches do wonders these days.
Project Wingman will fulfill your fighter jockey power fantasies as long as you can ignore the dearth of plane choices - or the absolutely awful end to the story campaign.
Partisans 1941 provides a fun way to stab Nazis even if the depiction of guerilla warfare on the Eastern Front is kinda sus.
This adaptation of the iconic tabletop game blazes its own path, but could have done with a bit more care and attention to make it truly great.
Iron Harvest captures most of the charm of Scythe and Company of Heroes while lacking some of the stuff that matter the latter so much fun.
Imperiums: Greek Wars offers a few twists on the usual 4X genre - like being more historical than Civilization's History-of-Mankind Thunderdome - but the execution isn't really there to make it worthwhile.