40k is literally the most generic sci-fi setting ever.
Anyway, you might want to check out
Strike Legion, which is a game that puts you in the shoes of the supersoliders of the Not-Federation fighting against the hordes of the Not-Imperium. Strike Legion is famed for its absurdity, with features such as personal scale weapons that can do damage to
planets, a stat system where 1 point in any skill makes you equal to the peak human potential (ie. 1 point in Martial Arts is equal to Bruce Lee), and a space combat system fleshed out for ship to ship combat that is then promptly thrown out the window in favor of giant robots.
Here's a Let's Read to show you what it's all about.You might also like
AT-43, a game about the space opera conflict of a divided humanity on an Earthlike world known as Ava as they struggle between a capitalist or collectivist future as they spread out into the universe seeking to better themselves and accelerate into the stars blah blah blah all of that is rendered pointless though with the arrival of the Therians, the actual human race who became posthuman gods a million years ago and ever since have been trying to arrest the heat death of the universe by Dyson sphering as many stars as possible and seeded Ava with human life in order to have them consolidate all the local materials. The Therians are the stars of the show here, because while they're infinitely more powerful than everyone else in every possible way, they're also fucking useless incompetents. Turns out living as immortal gods in the space internet for thousands of years has a way of making humans really lazy and egotistical, so you have things like Therian soldiers treating war like they're all FPS protagonists (not like bodily death really phases them), allowing the
actual soldiers on the other side a chance even though the Therians are nigh-invincible. They could win the war instantly if they actually gave a shit, but they're just so
addicted to fun that they can't. The most effective Therians are the equivalent of hardcore wargame players, being the only ones who can channel something resembling competence.