As we all know there are no mode other than the classic kill or be kill mode we have ATM.
So if we want to play in a "moded" game, ask your friends to help you to play a "moded" game.
Here're some exambles:
Attack and defend: 1 will be attacker and 1 will be the defender, defender must survive through a few waves (number of wave is decided by both players)...
Limitation: Have limit on abilities, control, unit types,...
The first and the last battle: no ghost, build FULL army, don't build any new units during battle and after it and hopefully what left of your army after battle can take down the statue.
Test: Just a test of the strength and other stuff of chosen units. (not really a mode)
Note that this is only a suggestion...no trolling.