3rd(?)/NES Gen: Super Mario Bros: Basically paved the way for 2D platforming. Arguably kick started the most popular gaming character in existence. Hard to top that in terms of influence.
4th/SNES Gen: Super Metroid: Built off the original Metroid and, in its wake, revolutionized the adventure genre. Largely responsible for the Metroidvania genre (even if it only contains half the name).
5th Gen: Ocarina of Time: Brought adventure games into the third dimension. Essentially set itself as a standard for which all 3D exploration games are judged by to some extent.
6th Gen: Halo: Combat Evolved: The game that made first person shooters a modern phenomenon and really popularized them. Laid the foundation for a generation and a half packed with FPSs.
7th Gen: Minecraft: Influenced gaming in so many ways outside of just its own popularity. Crafting mechanics are just one of the ways in which its impacted modern games.
8th Gen: Fire Emblem: Awakening: Obviously we're still in the midst of this, so this'll change, but Awakening revitalized turn based combat. Probably pales in significance to the others mentioned, but this has been a pretty underwhelming generation thus far and we're only halfway through it.









