Portal: The First Slice is the free demo version of the award winning Portal, developed by Valve Corporation. Portal is basically a puzzle game but in a (first-person) view, your main objective is to successfully get through the test chamber by teleporting with your handheld "teleporting device". Portal: The First Slice features the first 11 chambers (levels) to play.
Mac OS X 10.5.8 or newer
Intel powered Mac
1 GB RAM
NVIDIA GeForce 8600M GT or ATI Radeon X1600
Free download at steampowered.com