In rough order:
1) Dungeon crawlers. Anything RPG-ish that's light on story and heavy on combat, customization, and getting to the next level without dying. Includes everything from Nethack to Shin Megami Tensei.
2) 2D or 3D "Zelda-Likes," such as the Legacy of Kain games, ICO, Beyond Oasis, and Prince of Persia.
3) 3D platformers.
4) Horror-action games. Not just survival horror, but also including atmospheric shooters like The Suffering.
"'Casual games' are something the 'Game Industry' invented to explain away the Wii success instead of actually listening or looking at what Nintendo did. There is no 'casual strategy' from Nintendo. 'Accessible strategy', yes, but ‘casual gamers’ is just the 'Game Industry''s polite way of saying what they feel: 'retarded gamers'."
-Sean Malstrom
