The Stanley Parable

Out of "looks the same, but it's fairly unique" I would go with Outward. It's combination of action RPG, focused heavily on exploration (you have a map, but there's no indicator where you are), it has light survival and crafting features (just enough to supplement exploration, like RPG should, without being dominant mechanics) and it has split-screen coop. Not for everyone, but it has its audience who loves it.

The 1996 game DEUS (no relation to Deus Ex) and to a lesser degree, it's predecessor Robinson's Requiem.

1. It's Open-World FPS, where else do you find that?
2. You have 3 pages to check on yourself and to apply some kind of medicine (the game came with a book that explained what you need to do for what kind of injury, poisoning, disease, etc...)
3. Ever saw an FPS with a character catching cold?
4. Needing tranquilizers to get his heartrate down?
5. Overdosing on said tranquilizers for going on too long without resting?
6. Sewing your own clothes to visit colder regions to avoid the aforementioned catching cold (which can get deadly if you go on for too long without treatment)?
7. Being able to amputate parts of your body?
8. Screen turning black if you amputate both eyes? 
9. Needing food and water to survive in an FPS?
10. Needing to rest in an FPS?
11. Having dozens of potential death causes?

https://www.youtube.com/watch?v=LyNIcM2Gqpc

https://www.youtube.com/watch?v=guiEfcTaRV8&t=92s

Oh, that's a blast from the past - I know of this game, but never played it. Though I'd say, although very unique for its time, in last decade or so with so many survival/FPS/RPG games (my younger son's obsession with ARK comes to mind), it probably has a fair amount of (most likely unwitting) successors...at least to a degree (first time I heard about it was back in 2005 when someone compared some of the things Boiling Point: Road to Hell was doing to DEUS).

There is no game like Kingdom Hearts Chain of Memories and its remake, the way that cards are used both for the ARPG combat and for the level design of every world, is completely unique to that game.

Lemma look into it. Never tried that one.

Sonic.

Katamari Damacy



It had many sequels, but all like itself.


Herdy Gerdy



I haven't played a herding simulator other than some simple side quest in Zelda.


Dungeon Keeper stands out as well

2D or 3D? I feel like there are a ton of alternatives to 3D Sonic (for boost formula, a game like MarioKart and time trials would scratch that itch) (adventure formula is kinda just your standard 3D platformer from the early 2000s) (IDK what scratch your looking to itch with Fronteirs, that’s a weird one). As for 2D, I feel like there’s an indie project popping up every day attempting to recreate the classic 2D Sonic formula.

Mainly the 2D games. You don't see a speedy platform like that.

Nobi Nobi Boy