Flat Zone is an unlockable stage in Super Smash Bros. Melee. The place is located in Superflat World, and is Mr. Game & Watch's home stage. It is unlocked by beating Classic or Adventure as Mr. Game & Watch at least once. The unlock match for Mr. Game & Watch takes place here.
Flat Zone is set within a Game & Watch system of the Widescreen series, with the title Smash Bros. on the right-hand side. The stage is based on Helmet, Oil Panic, Fire, and Manhole. Its most regularly-occurring gimmick is a Game & Watch-like figure, holding up platforms in the style of Manhole. The figure will move occasionally, causing some parts of the platform to move somewhere else.
Periodically, items such as wrenches, buckets, and other tools will fall from the top of the stage in the style of Helmet. Although this does not initially sound too bad, the tools are devastating to lower handicapped or heavily-damaged players due to their high level of knockback, being able to KO them at mid-to-high percentages with a direct hit. Fortunately, the falling tools can be avoided by air dodging, rolling, or by simply moving out of the way as they start to appear.
More rarely, a Game & Watch-like man carrying a oil drum in the style of Oil Panic will pass by. However, he will trip at a random spot and drop the oil. This will spill it onto the ground, making the area very slippery and difficult to traverse by running or walking.