Inspired by this thread.
Having immersed myself in the medium* lately, here’s what I can remember:
2-D Platformer
Super Mario 63
You may be rolling your eyes but this game…is like the framework of Super Mario World, mixed with the physics and plot of Super Mario 64, the graphics of Yoshi’s Island, and the music of Super Mario Galaxy.
Adventure
Cave Story
Tower Defense
Bloons Tower Defense series (with 3 being the pinnacle)
RPGlike
Sonny
Puzzle
…there are so many, it’s hard to pick just one. Really, free online games represent the triumph of the Puzzle genre.
A few: Loops of Zen, Factory Balls series, Shift series
Shoot-em Up
Frantic 2
Shooter (3rd person)
Iji
MMORPG
Kingdom of Loathing
Gimmick
Upgrade Complete!
*Have these games even been around in force for 10 years yet?