Bulletstorm has red barrels that explode when you shoot them. Why? Because green barrels don't explode, duh.
The balance between intuitive gameplay and original gameplay can be a difficult one to walk for a game designer: How do you try to stand out from the crowd when gamers have become so accustomed to conventions? Your health meter is green; a red flash on the screen means you're being injured; A is "yes" (or the jump button) and B is "no." Say you wanted to put barrels in the game that would explode when shot - what color would you make them? You certainly don't want to make them red, since every action game has red barrels that explode when you shoot them.
But that's exactly what gamers have come to expect. A red barrel isn't filled with delicious salsa: It will explode if it gets hit by a bullet. In a post on the studio's official blog, a People Can Fly rep explained that gamer expectation had shaped the development of hyperkinetic shooter Bulletstorm, because people just wouldn't shoot green barrels.
"We made a stab at trying something different, instead of going with the cliché. In the beginning we had green barrels, but people didn't get it right away," wrote designer Arcade Berg. "They got completely ignored by the players and no one guessed or assumed that they were explosive. Why not? Because they weren't red. Everyone knows that only the red barrels are explosive."
In a game intended to be as fast-paced and frantic as Bulletstorm, he elaborated, it was important to provide visual cues that a player could easily identify and quickly process. That means making explosive barrels red. "There's no time to analyze objects on a detail level, so the shape and color have to be enough. It became apparent for us that the most efficient way to communicate its purpose was to make it red."
And yet the developer's work wasn't done there. It turns out that a surprising amount of effort and thought has to go into something as simple as "paint it red."
If you're interested in game design, the hows-and-whys of explosive barrel design, (or just interested in Bulletstorm), the full blog post is a fascinating read. I would like to point People Can Fly at 2009's Borderlands, which had red barrels, green barrels, orange barrels and blue barrels - they all just did different things when you shot them.