The 2 hour refund window is for automated refunds, you can still make a request if you’re past that - it’s just going to need a human to take a look at it. I’ve once succesfully returned a game I’ve played for about 5 hours because it had game-breaking bugs and ran like crap for no reason, and it got accepted within a day without an issue.
So Helldivers owners have a chance. I’m assuming that Steam’s Customer Support department is having some kind of an internal discussion right now on how to handle this case.
Way less gross. Human and centaur are both intelligent, can communicate, and give consent, so it would be fine. With a horse (which has none of these things) the centaur would be committing bestiality.