The really good games started coming out somewhere in the late '90s, I think?

Many people have 1998 as the year when the most “best games of all time” came out, though 2001 and 2003 were also unbelievably stacked with all-time bangers.

Now that said, it heavily depends on the platform. For PC gaming, the peak might have been the early 90s, when we were seeing stuff like Rollercoaster Tycoon, SimCity 2000, Doom, Civilization, etc.