What is a game or games that you think are an absolute must-buy?

Seconded, Ive replayed that game like 3 times already. The first one had an amazing story imo, even though the puzzles could be a little difficult, especially the hidden ones. I've sadly only played a few hours of the second one, due to the game engine change (from Source to Unreal I think?) movement feels too different and the story didnt get me hooked right away like the first one did. Still going to finish it at some point though