Valve's Erik Wolpaw has promised that players won't need "twitchy ninja skills" to complete Portal 2's puzzles, despite the acrobatics seen in trailers so far.
"You have to sweeten it a little by having someone do some crazy ninja moves," Wolpaw told Joystiq of Portal 2's trailers, explaining that watching someone work out a difficult solution isn't as much fun.
Valve found that the vast majority of players who didn't finish Portal quit after one of two puzzles requiring very precise controls.
"One of the things we learned after releasing Portal 1 was that there were a couple puzzles in Portal 1 that required some sort of twitchy ninja skills to actually execute the solution," Wolpaw explained.
"If you ... struggle with the controller for twenty minutes to execute the solution that you already know, almost universally we found that it was frustrating people."
"We've actually gone the other way, and tried to make it more about actually thinking the puzzles through and less about struggling with the controller to execute them," he added later, citing more forgiving portal entry as a physics tweak to this end.
Players will be introduced to new concepts gradually, the writer explained.
"We're going to train you. At no point are we going to ask you do something that we haven't prepared you to do," he said.