Portal: First Slice

Portal: First Slice is the demo version of Portal. It was originally available on Steam for free for any Steam user using Nvidia or ATI graphics hardware as part of a collaboration between the two companies. It also comes with Half-Life 2: Deathmatch, Peggle Extreme, and Half-Life 2: Lost Coast. The demo contains the first ten test chambers. Since then, Valve has made the demo available to all Steam users.