It also helps indicate when one puzzle ends when it is placed next to an exit door. The Emancipation Grid keeps test items from entering another puzzle or part of a puzzle. These can actually be helpful to players in certain situations where it is too difficult to return to an earlier part of the puzzle if the current solution isn't working out.Įmancipation Grid and Pneumatic Diversity Vent Conversely, in cooperative levels it does not take very long to recover from them so they may be liberally applied. In single player these are used to signify major errors, since a re-load is usually required between deaths, and should therefore be relatively easily avoided. What they are isn't as important from a mechanical point of view since they simply form the in-game explanation for how the player gets to the next level. These are the actual entry and exit points for levels. Each of these kinds of doors should be different enough in appearance to prevent confusion among players.įor example, levels in the underground portion of Portal 2 begin and end with push-bar type doors and a variety of doors in between, depending on context.ĭoors should be set up so as to prevent any attempt to wedge test items between them. Finally, doors can be used as a temporary obstacle within a puzzle. Second, to indicate that two puzzles are not related to each other. First, to signify the beginning and end of a level. Others will be one way - in order to return to a previous state the puzzle must past through intermediate states.ĭoors have three purposes.

Most will be two-way, meaning the state can be easily reversed.

The connections between the nodes are the mechanics. One way of breaking down the mechanics of Portal 2 is to look at each puzzle like an abstract graph, with nodes connecting each state.

1.13 Thermal Discouragement Beam and Catcher.

1.4 Emancipation Grid and Pneumatic Diversity Vent.

1.3 Crushers, Slime, Pits, and Shredders.

Portal 2 no steam and exit