Mad Max is a fun one that got overlooked.

I like to recommend Observer when this topic comes up. It's such a cool game and the setting is pretty creepy and disturbing. There is no combat so that's a turn off for some people but the game is really fun. It's also kinda similar to Cyberpunk for people that liked that setting. You have a similar scan feature you use to do investigations and can switch between scanning organic or tech matter.

Eternal Darkness.

I was skeptical about that one because of how it looked. I thought it would just be driving around in a big empty desert. I ended up just getting it and man is that game fun I totally recommend it for anyone who enjoys open world games

I was very skeptical of new world when it first released due to the bricking of gpu's and whatnot but a friend recently gifted it to me because he needed a healer and its actually been a lot of fun. Would recommend if you enjoy open world games with a vast amount of trade skills to waste time on.

SOMA is also pretty good if youre looking for more of a single player experience

Ghost of a Tail. You play as a mouse in a fantasy setting where other animals like rats, birds, and weasels ext. are the dominant species. The plot revolves around you trying to save your wife after being caught by the rat military during a round up of suspected rebels. You have to hide and sneak your way through there castle looking for clues and using disguises to trick them as you go. The story and writing are amazing along with the characters. The game does have some more dark themes to. I stick to shooter and strategy games and got this because "OMG I get to play as a cute mouse!" But I was so surprised by it that I played it again immediately after the first.

I think Alien Arena: Warriors of Mars is an underrated gem. Always fun to play with friends. Smooth and fast gameplay. Takes some time to learn all the tricks but then you have a game that you never finish. Is free on Steam.

These are fairly well known, but.. The Binding of Isaac Deep Rock Galactic Darkwood Circuit Superstars (needs more content tbh) Battlebit Remastered (still in beta) Foxhole Trailmakers

Tortured Souls.

It’s as close to old school Silent Hill that I’ve ever seen. High recommend.

ROCK AND STONE!! Also I love Trailmakers!

Rock and Stone to the Bone!

The story is pretty generic and the dialogue is obviously written by a foreign person, but I loved Outriders. The gameplay is so fun, the ability spam is addictive and there’s tons of different builds

Is Deep Rock Galactic any good if I don't have a dedicated group of friends to play with?

Hunt Showdown!

My favorite game.

Another hidden gem I think is Valley. The gameplay is quite original.