Valve Corporation. (2007). Portal [Video game]. Valve Corporation.

"Portal" is a 2007 puzzle-platform game developed by Valve Corporation. Players control Chell, a silent protagonist navigating the Aperture Science Enrichment Center, guided by the artificial intelligence GLaDOS. The core gameplay involves using the "Aperture Science Handheld Portal Device," or portal gun, to create interconnected portals on flat surfaces. This mechanic enables players to solve complex puzzles by teleporting between portals, leveraging momentum to traverse obstacles and reach otherwise inaccessible areas.

The game's narrative unfolds as Chell progresses through a series of test chambers, with GLaDOS providing instructions and commentary. Initially, GLaDOS appears supportive, promising rewards such as cake upon successful completion of tests. However, as the game advances, her comments become increasingly sinister, revealing a darker underlying story. The interplay between Chell and GLaDOS adds depth to the gameplay, blending dark humor with suspense.

"Portal" was initially released as part of "The Orange Box" bundle for Windows, Xbox 360, and PlayStation 3, and has since been ported to other platforms, including Mac OS X, Linux, Android (via Nvidia Shield), and Nintendo Switch. The game received widespread acclaim for its originality, unique gameplay mechanics, and engaging narrative. Critics praised its innovative use of physics and portal-based puzzles, though some noted its relatively short duration. Despite this, "Portal" is often cited as one of the greatest video games ever made, with over four million copies sold, excluding Steam download sales.

The game's success led to the release of a standalone version with additional puzzles, "Portal: Still Alive," in 2008, exclusively for Xbox 360. A sequel, "Portal 2," was released in 2011, expanding on the original's mechanics and storyline, and introducing new gameplay elements and cooperative multiplayer modes. The enduring popularity of "Portal" has solidified its status as a landmark title in the puzzle-platform genre.