What is Dumpster Gang?
You play a raccoon. Up to three friends play the rest of the gang. You break into buildings, knock over bins, raid snacks, and carry off anything shiny that is not nailed down, while a pest-control worker works his way through the level trying to put you in a cage.
The movement is the point. Raccoons sprint, climb walls and crawl through vents, so the route into a building is rarely the door, and almost everything in a level can be picked up, thrown or smashed. Heavy loot needs more than one pair of paws, which is where the co-op stops being cosmetic.
Between jobs you go home. The hideout is where stolen junk becomes decoration, where you customise your raccoon, and where hats with their own abilities are unlocked.
That is the shape of it as described by the people making it. How any of it is balanced, how long a mission lasts, or how hard the Exterminator is to escape has not been explained by anyone yet, and this site will not pretend otherwise.