Openworld\sandbox: Minecraft.
It didn't invent things, but it made the most of it's raw components like proc. generation, crafting, impacting world by just placing a block, implementing basic algorythms into the game by redstone and modblock (?). And it bssically created the indie market.
Old role-playing: BG \ NWN (IDK what defines RPGs now)
Adapted tapletop systems, created an environment for your own modules, a big inspiration in this genre.
Sports: Unreal Tournament \ Quake 3 \ Counter Strike 1.6
That's when cybersports start to be known by masses and whole games begin to be made exclusively for it. Not ideal, but highly refined competitive games that made a huge impact on how games are made.
It will save more of them if they stop.