The game environments in Uncharted 3 are full of details and dense with objects. Thus, it is easy for important things to get lost. Thanks to user testing sessions, it became evident that when edge-grabs are difficult to spot, players were finding themselves stuck, not able to progress further in the game. It was even more frustrating when players repeatedly tried to jump and grab things that looked to be climbable but weren’t. Developers at Naughty Dog implemented a system to record “Bad Jumps” events: they recorded the position of the main character every time the player pressed the jump button but did not end up grabbing a ledge – that is, Nathan Drake just jumped up and down. A little red sphere was implemented to signal to developers where the features that looked like an edge-grab were. Changes were later made by artists to make such ambiguous features look less “grabbable”. This fix made the gameplay much more fluid and rewarding.
Lemarchand, R. (2012). Attention, Not Immersion: Making Your Games Better with Psychology and Playtesting, the Uncharted Way. Proceedings of the Game Developer Conference 2012. Retrieved here: http://www.gdcvault.com/play/1015745/Attention-Not-Immersion-Making-Your (GDC Vault free content)