Portal 2 developer commentary: Difference between revisions

=== Tag: The Power of Paint ===

| Similar to the way the student game Narbacular Drop became the original Portal, the paint mechanics in Portal 2 come from a student game,  Tag: The Power of Paint.  The repulsion gel in Portal 2 is modeled after the bounce paint from Tag, but was redesigned to fit better within Portal.  The original bounce paint always bounced the player at a fixed height and activated whenever the player touched the paint.  We changed the repulsion gel to reflect the player's velocity, such that they will bounce back up to the height that they fell from.  This mechanic lends itself better to puzzles involving portals because players have to think about gaining and preserving height.  We also changed the repulsion gel to only activate if the player jumps off of, or falls on to the gel.  This was done because players would often accidently walk onto repulsion gel they didn't see and then trigger an unwanted bounce.  This was a particularly nasty problem in Portal 2 because the player couldn't get rid of paint once it was applied; whereas in Tag the player can erase paint at any time they want.

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