It depends on what you like so I will make my selection as varied as I can.
My picks are:
(Whichever know a deal that cost less than what it states on steam if you want to buy it)
Heard it was good from a review but haven't played it yet. Still trying to finish other games I have before getting to it.
Does require patch because of the shite port like Saints Row 2 but like Saints Row 2 worth the play. It is more gothic than Gothic which shouldn't really turn you off because the characters to me were fun to interact with and I was allowed to do stuff at my own pace and choose not to do things.
(Find it cheaper than the steam price as well)
Heard it was good but have only played 1. Basically tower defense with guns.
Saints Row 2
(Once again can be found cheaper than that price)
If you liked Saints Row 3 and wanted better gangs. This is the game for you. Requires something to install to reduce bugs but it is fairly easily install and there are multiple videos in helping people download it.
Specifically the custom maps. There are various to pick from which can include new maps made by the modders or something like Kino Der Toten in COD WAW. Best time I have ever had when zombies were involved was with this game.
People say the first is better but they don't know what they are talking about. Basically New Vegas but Star Wars. Less freedom like where you can go but the player still has choices in what they want to do. There is also a character which really makes you think about your choices that does improve the game.
Grand Theft Auto: San Andreas
(If you want to buy it. I know a bundle which is cheaper then buying them separately. Don't buy the standalone not worth it compared to the bundle. Like the same with the Handsome collection if that had one more game)
Best in the series not more needs to be said.
Amnesia: The Dark Descent
( Can be bought cheaper and might as well buy both games together if you are interested enough to play the sequel)
Heard this game is the best but never played it. Maybe because I am too scared.
(I think it is cheap but don't really know)
More of a thriller I think but I put it here. It is great like Amnesia but in a different way.
Played it and enjoyed it. Characters are great. Platforming is enjoyable. All in all the most fun I had with a platformer.
Says you can't run it but I think you can so this is a maybe buy for you
Type in gpu as your GPU. Type in the RAM then search the game.
I have this on my PS4. Is fun and worth the buy. Combat fun. Story fun and the main character is hot so the game has everything.
If you do decide to buy this I can think of a cheaper price for it and a video to watch if you are having trouble making a consistent framerate.
I can speak about others but I'll leave it at that. Hope you enjoy.