I'm requesting for recommendations for games that stand out from the rest in their genre, and not in the sense of being the best game in that niche but actually bringing something new and innovative to the table. I've not had much experience in gaming, but I have a few games to give you a hint on what I am talking about:
Superhot: Time only moves when you do
Viewfinder: Convert 2D pictures seamlessly into interactive 3D environments
Superliminal: Change size of objects by working with perception
Portal: Portals
Scribblenauts: Summon objects by describing them in a notepad
I am not focused on the story, no. of hours of playtime, date of release or its popularity. It just needs to be playable and be enjoyable (and be available in PC).
I am not sure if it qualifies but Paradise Killer is pretty unique all-around. It may seem walking-simulator-ish but the presentation and the overall game-design are definitely a stand out. You're trying to solve a murder mystery and it's completely up to you as the player to decide when you've gathered enough information to make a conviction. There is practically no hand-holding either which is quite rare for a mystery solving/detective game.
I know it might not exactly be what OP asked for but I think the game is worth being recommended more.
There is really something very different about this game. If you point to any individual part of it, there are other games that do that thing. But all together, it's quite unique. And it's a pretty fun game.