Double Deck is a battle course in Mario Kart 64. It takes place in a labyrinth with decks.
The racers begin the battle on the ground floor and then can go up or down slopes to the upper or lower decks. The lower deck is colored green, while the upper deck is red. All have a wide rectangular path. At the top, there is a large square gap, which allows the racers to fall back down to the ground floor.
Mario Kart 64 instruction booklet: "Square" shape floors four levels high are connected with ramps allowing you to go back and forth. Because the total area of the floor is wide, you might have lots of trouble trying to find your opponents.
Mario Kart 64 web page: Even though Double Deck is about the same size as Block Fort, it seems like the largest of the Battle Mode arenas. Double Deck has multiple levels but the different sections are not color coded, so it can be difficult to locate your opponents. This is a good arena to play with four players.
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