The general rules are as follows:
"Here it is, folks, the second of GetMeOffTheMoon's Neo Devroom Events! The name of the game is ruin conceptualization--Mega Man's been through tons of ruins with all sorts of unique motifs behind them, so we're on the lookout for rough concepts that could provide the foundation for a brilliantly engaging ruin.
Now we're not looking for maps or intricate layouts here. We're looking to get a general feel for what these ruins are going to be like. Images are optional, but they can serve as a huge asset to your designs. To add some depth to the event, we're also requiring a minimum of one environmental hazard to compliment your ruin description. Of course, if you can describe your ruin very well using text only, you're more than welcome to go for it."
Of course, what's an event without cool prizes? The first-place winner will receive a framed Mega Man Legends 3 poster, autographed by Keiji Inafune. Other prizes for subsequent placing winners include a spiffy Mega Man Volnutt t-shirt, and a custom-made hardcover Japanese-bound unlined notebook featuring a painting of Mega Man exploring your ruin.
The contest doesn't officially begin until tomorrow, June 1st, but it couldn't hurt to get a head start. Full contest rules can be found here, and you can also join in the discussion on Capcom Unity.