Imagine a bunch of magnetic blocks that you can stick to your refrigerator. If you put them in the right spots on the fridge door, you can drop a marble from the top of the fridge and have it bounce and fly about until it reaches the target at the bottom. That's the basic idea behind Marble Run, a cooperative webtoy that won the Mozilla Labs Game On open Web game development competition. And yes, it's cooperative, because you're building just one part of a gigantic, continuous marble run with thousands of other players, like refrigerators stacked from here to the moon. Just pray that the milk is in one of the lower ones.
On each, shall we say, "fridge door," you'll find a 10x15 grid with a marble in the top-left corner and the finishing target in the bottom-left corner. Your goal is to get the marble to the target through whatever means possible. Of course, you could just start the machine and let the marble drop straight down, but where's the fun in that? To the right of the grid are a couple boxes full of bricks. Click and drag the bricks into the grid, or click a brick and "paint" them into position, then click each brick to rotate them 90 degrees. How long of a track can you create?
To help you go the distance, there are a few special bricks, such as teleporters and trampolines, that can send the ball flying in all different directions. When you complete a track, you can submit it to the database (be sure to add your name and a title). Each track added boosts the collective track length, and new special pieces are added the longer the track grows!
While addicting in an oddly simplistic way, there are a couple of drawbacks in the Marble Run system. First, with the ability to submit any completed track, some less-than-family-friendly designs have popped up in the database. There's a button to report inappropriate tracks, but as they are not immediately removed, they may still appear, which is the sole reason why we've given this game an Orange rating. Also, for whatever reason, pieces may not behave very predictably at times. It's fun to exploit some of the quirkier characteristics of some blocks (such as trampoline blocks that work as propulsion systems when laid sideways underneath the marble), but occasionally you might not get the same results everytime. Some tracks in the database, while they may have worked for the original poster, might not work for everyone, for whatever reason.
Still, there's a lot of game to be found in such a simple webtoy. You might challenge yourself to produce a track that results in an exact length, or try to see what designs you can make with the blocks. The community element adds to the fun, as you're all working to fulfill a common goal. Give Marble Run a try and see what happens when your track is put into motion.