The games in the genre like Doom came out in the '90s, but it wasn't just young people playing it, more like uncles generation, I suppose that's why they were still boomers. I feel the audience got younger (taking the millenial generation) when Quake really focused on the multiplayer scene beyond some Mac and Linux modding and LAN parties. That was Quake 3 I think ? The one on Dreamcast. e: and obviously also the Counter-Strike era that came just after. Boomer shooters are the ones before that.