Portal is a 2007 single-player first-person puzzle-platform video game developed by Valve Corporation.
The game primarily comprises a series of puzzles that must be solved by teleporting the player’s character and simple objects using “the handheld portal device”, a device that can create inter-spatial portals between two flat planes.
|By Kaini [CC-BY-SA-3.0], from Wikimedia Commons|
The game’s unique physics allows momentum to be retained through portals, requiring creative use of portals to maneuver through the test chambers.
— Wikipedia on Portal (video game)
2012.04.21 Saturday ACHK