Was Portal Originally a Mod?

Portal Reloaded is a free, community made modification for Portal 2. The mod builds on the concepts of the main game by allowing you to place a third portal, which enables traveling between two different timelines.

What game was originally a mod?

Some original mods, such as Counter-Strike, Team Fortress, Day of Defeat, Ricochet, The Ship and Alien Swarm (originally a mod for Unreal Tournament 2004) have been "adopted" by Valve and made into commercial games.

What is the original portal?

Portal is a 2007 puzzle-platform game developed and published by Valve. It was released in a bundle, The Orange Box, for Windows, Xbox 360 and PlayStation 3, and has been since ported to other systems, including Mac OS X, Linux, and Android (via Nvidia Shield).