This is actually an isometric pyramid-like structure of tri-colored cubes. Q*bert's purpose is to hop around the tops of these cubes, changing every square to a specific color.
Avoid these kinds of enemies:
Killer Red Balls of Doom.
Coily
Ugg
Wrong-Way
Pogo-Guy (Shy Guys that hops with Pogo-Sticks)
Cobrat
Hoodblasters