I don't think I can overstate how good this game is. The gameplay was a great blend of stealth, cheap jump scares, and combat action. Combat can be as varied as you like; you can choose to sneak around rather than fight everything, you can go full-on soldier and murder everything, and you can repair (and later build) turrets and let them do the dirty work. I had a lot of fun trying to set up turrets in such a way that they could kill the "thing" (spoiler, can't tell you) when it spawns in certain areas. The skill trees make for some good customization for whichever play style catches your fancy and are mostly useful, with only a few seeming like a waste.

On Normal, the game gets pretty easy later on if you're any sort of completionist and thrifty with your loot. If you are that sort of player, I suggest turning up from Normal, even on your first playthrough.
I've only seen one ending so far but I enjoyed the game enough that I'm about to start again with the Typhon skill trees only.