Games that are visually stunning.

[BENZOOKA]

Games that I can remember where I've actually stopped to admire the gameplay visuals. In no particular order:

Lotus 2 (Amiga)
Rainbow Islands (Amiga)
Fallout 3
Bastion
Colin McRae Rally
Counter-Strike: Source
Half-Life
Half-Life 2
The Witcher 2
Metro 2033
LIMBO
Rise of Nations
GTA 3 & 4
DiRT 1 through 3
BioShock 2
Deus Ex: HR
Dragon Age: Origins
Operation Flashpoint
NFS 2, 3, Underground, Shift 2...
NHL 12
Eufloria
Borderlands
Morrowind
Oblivion
Skyrim
Portal 1 & 2
Mirror's Edge
UT 2004