That is the point, there are a lot of crappy games in Steam and min sys specs of 8 GB RAM free, even for messi sidescrollers. Fortunately there are exceptions, mainly in somewhat older games, where the devs still had to score with quality and playability on the PCs of that time, such as the aforementioned TombRaider series at that time or the DarkMessiah, The Dark Mod that does not need to hide from many commercial games either, and others that prove that even a crappy laptop that cost me €350 can be used to play them with more than 30-40 FPS and without taking up more than a few Gigs.

Also a good source of free games is the IT Academy DigiPen, wich offers a huge catalogue with hundreds of games of any kind, the best works of the students as free download. Some of these also in Steam, search DigiPen there. https://games.digipen.edu