I've been recommending this game in many threads, but I thought it was about time to make my own thread. This game is in a 40% sale in Steam for a few more days, so if you're looking for a single player game consider Outer Wilds. It's a really unique experience, best played knowing as little as possible, so I won't describe the game in much detail. It's a game where you explore a small solar system with some really imaginative locations. It's one of the few games that has given me the kind of awe you get as a child when you explore in games. If you're interested in getting Outer Wilds I also highly recommend the DLC Echoes of the Eye. It's quite possibly the best DLC I've ever played.