Does this game have an option to invert the mouse Y-axis anywhere? I'm probably being blind but I can't find a setting anywhere in-game.

No, no such setting. Perhaps you can emulate it through your mouse driver?

I had a quick look on PC Gaming Wiki, tried using the Polynomial mouse inverter mentioned there, inverts the input in Windows but not in the game. Hopefully will get patched in soon, involuntarily looking at the sky ruins the atmosphere somewhat.

Dang. I knew there was something I forgot to check before I preordered this. I always forget to check for this, and now I have a bunch of games with no mouse invert.

In my experience, it rarely gets patched in later, since we're apparently a minority, but sometimes it does. I'll keep my fingers crossed.

I'll try a couple of mouse inverters. To my knowledge there are only 2 or 3, and I know one of them, mafmouse, doesn't support 64 bit Windows. If anyone finds a mouse inverter that works for this game, please post.

The mouse invert option is a standard PC option since years. I use it since Terminator: Future Shock. It makes me a bit sad that i have to ask if that option is included, before i buy a game.

I asked for that option before i bought the game and they answered back, that they will add it along with a mouse sensivity option.

Thanks for letting us know. I'll be looking forward to that. I hope they follow through.
I'm currently enjoying it as-is, in spite of my occasional looking up when I meant to look down and vice versa. The gameplay is slow enough that it hasn't been bothering me as much as it would in a fast-paced FPS game, but it's still annoying. I've been reversing the Y-axis on all my first and third person games since 1993, so it's very ingrained in me, and I can't play any other way after 20 years.