Okay so get this.
Use either Kalph's or Xalos' elevator bricks + events with zones, and VCE. Make it in a low-lit tower with obstacles coming from above and enemies coming from the walls or firing from the walls in waves. Include multiple levels, where after the elevator comes to a point, it stops, and a giant door opens to reveal a prep room and/or checkpoints. In this room, if the entire team dies, they restart at this level. If the entire team dies again, then everyone goes back to the start of the campaign. Include multiple of these transitions, bosses, power ups, weapon shops (or first come first serve, alternately make it class-based). Complete with 5-10 levels, each increasing in difficulty. Enemies can be anything from zombies to an infiltrating armed forces.
Elevator firefight.