Fifth generation:
The sheer number of ground-breaking titles is astonishing. It was the advent/rise of 3D graphics in games which meant devs ahd to think up new control schemes and games pushed lots of new ground.
Started this gen: Gran Turismo, Tomb Raider, Resident Evil, Metal Gear Solid (yes I know, Metal Gear was out before), Half-Life, Starcraft, Age of Empires, Unreal.
Look at influence of this gen:
- Half-Life: start of a huge and revolutionary shooter franchise, introduced proper storytelling, AI, proportional damage, puzzle solving etc. in the FPS genre, gave birth to Counterstrike, Team Fortress, Day of Defeat and a huge range of user mods and later Steam
- Gran Turismo: Really the first driving sim to release on consoles, was that start of a 5 game series with each selling nearly 10 million copies
- FFVII: First FF to release in Europe, showed JRPGs could be popular outside of Japan
- Goldeneye: Revolutionary and showed FPS could work and be popular on consoles
- Zelda: OOT: First 3D Zelda and is still considerred one of the best games created by many
- Resident Evil: Popularised the Survival-Horror genre and started a franchise that's still going strong today
- Silent Hill franchise started this gen
- Metal Gear Solid: Amazing storytelling and popularised the stealth-adventure genre
- Tomb Raider: started this gen and showed there was a market for a platform game with mature undertones (although likely played by pubescent teens!) Likely influenced Prince of Persia and Uncharted.
- Mario 64: Great platforming game which laid the foundations for all 3D Mario games.
- GTA and Driver started this gen and sowed the seeds of the sandbox games of later gens
- Introduction of analog stick followed by the dual analog control scheme utilised by every console since
- Introduction of rumble
- Tekken and Virtua Fighter games started this gen
- Starcraft came out this gen and went on to sell > 10 million copies and spawned a sequel. Bacame a national sport in Korea
- Age of Empires released this gen and spawned a 20 million unit selling franchise.
- The popularity of Quake II online signalled the rise of online gaming with MP focused games like Quake III Arena, Unreal Tournament and Counterstrike and becomming hugely popular
- Unreal franchise started this gen
- Baldurs Gate released and the advent of Bioware as a top WRPG developer
- Original Fallout games released this gen
I'd say the last two gens owe a lot to the minds of the fifth gen.