This game is the reason why a guy [the legendary u/-YoRHa2B-] started working on dxvk, to make this game compatible on linux after it released. Valve hired him and made Proton out of it. The result is the Steam Deck, this remains one of the best games for the SD.
Just confirming that you did reload your save after “beating the game”. I remember when the game came out people were only partially beating the game because they didn’t know there was more!!!