Deus Ex demo. 

It's the near future, and the world is a much darker place, ruled by 
corporations and ruthless governments. Now a terrorist group is threatening 
to throw the world into chaos, and it'll be up to you, playing as a 
counterterrorist agent, to determine what's going on.

Minimum Requirements:
At least 300-MHz Pentium II, 64MB of RAM, and a DirectX 7.0a-compliant 3D card. 

Recommended:
Athlon or Pentium III-based system with 128MB RAM.