5. Portal (4 hours)

The campaign did not last long, but Portal is one of the most original games to date though.

This 2007 game obviously did not have the longest single player campaign made to date, but delivered some of the most original gameplay seen in a video game to date. Focusing on portals, the game let players open portals on surfaces like walls and floors. In the game, a connected pair of portals would allow players to go through one portal and exit through another.

This great gameplay mechanic was needed to get through the game’s different levels (known as test chambers), and plenty of lateral thinking was required in order to get through the most difficult chambers. The game also featured one of the most memorable video game characters ever too. The artificial intelligence known as GlaDOS delivered most of the game’s witty script, which had no shortage of funny lines… So even if Portal isn’t the longest game around, it is still a bona fide classic worth playing (or replaying) again.