a treasure hunt in a custom build
^ a treasure hunt in a custom pirate ship
a challenge that involves less 'lol press space!!!', and more thought and logic
^ the same thing, except very fast paced and if you forget up a challenge, you go right to the next one, warioware style
something involving grind rails
^ parkour racing involving grind rails
a TDM with bases actually within visual range of eachother, fully constructed out of bricks, and not involving vehicles at all
^ a mario-kart style tank arena with no bases, entirely constructed out of destructible bricks (up to and INCLUDING the ground)
a bombing run 'CTF'; in other words, get YOUR flag to the enemy base before they do the same to you
^ a neutral flag CTF where the flag's position is randomized or selected from a set amount of potential spawns, so players can't just camp the one and only spawn
a skateboard race (uxie's are startlingly good at not falling through bricks, so you could probably just build the map)
^ preferably styled after
City Escape^ a parkour race that, at some point, involves both grind rails and skateboards
^ a marathon crouch race that involves tanks, flags, grind rails, skateboards, horses and random path generation built entirely out of bricks