The following is the list of the latest of preview games out on the web.
This list will be updated periodically.

Anachronox

Command & Conquer: Tiberian Sun

Caesar III

Daikatana

Deus Ex

Diablo II

Direct X ver 6.0

Dungeon Keeper II

Deathtrap Dungeon

Duke Nukem Forever

Everquest

Fallout 2

Half-Life

Heroes of Might and Magic III

KKnD2: Krossfire

The Lady, The Mage and The Knight

Messiah

Mortal Kombat 4

Montezuma's Return

Monster Truck Madness 2

Myth 2: Soulblighter

Need For Speed III: Hot Pursuit

Prince of Persia 3D

Prey

Startcraft Expansion Pack: The Brood Wars

SimCity 3000

SiN

Wizardry VIII

X-COM: Interceptor