Exploding red barrels are a video game cliche. The people making the video game Bulletstorm wanted exploding barrels in their game, but they dreamed to make their barrels green. Then they woke up.
Well, before they woke up, they put green barrels in their game. And they tested their game on real human beings. Here's what happened, as recounted on the official blog of Bulletstorm development studio People Can Fly:
In the beginning we had green barrels, but people didn't get it right away.
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. There's a lot of stuff going on in Bulletstorm at the same time, so it's vital for us that the player can quickly read the environment and act intuitively. This is especially true since you can leash and kick objects as well so they can be flying all over the place. There's no time to analyse objects on a detail level, so the shape and colour have to be enough. It became apparent for us that the most efficient way to communicate its purpose was to make it red.
"Just making it red" seems like a straightforward approach...
See? We are the problem. We shoot red barrels with vigor, while letting green barrels stand intact. The excellent post on this subject goes on to explain just how People Can Fly settled on the proper barrel shape for their Bulletstorm barrels.
Read all about it. And, next time you see something green in the game, shoot it. You will then no longer be part of the problem.
We had to use Red Barrels [People Can Fly blog]