Portal 2 is a first-person puzzle video game that was released in 2011. It is the sequel to Portal, which was released in 2007. The aim of the game is to solve puzzles while navigating the character through the portals. There are two game modes: single-player campaign and co-operative campaign. Users can also play puzzles developed by community members. Each level has obstacles that must be passed in order to progress to the next level. Characters can interact with the objects in the game. Some obstacles include toxic liquids, objects, and bottomless pits. Falling into toxic liquids and pits kills the character immediately. There are checkpoints in the game where users can start from if they die before finishing the level.
Most of the game takes place in testing rooms inside a science facility. In these levels, players can see a clear exit. In other levels of the game, the objectives may not be so clear. The player goes through a tutorial level at the start of the game to get familiarized with the controls. There are also new elements added that were not present in Portal. These are:
• Thermal discouragement beams
• Hard light bridges
• Gels (orange propulsion gel, blue repulsion gel, white conversion gel)
• Aerial faith plates
• Excursion funnels