To do it, you have to post a rule that should be in the game
For examples, I'll start off:
1. Marines shouldn't be able to shoot and kill things that are 100 feet in the air
2. Barracks shouldn't be able to train units in seconds. How is possible that someone gets training that takes weeks in seconds?
3. Zerg with wings shouldn't be able to fly through space. Why? BECAUSE THERE'S NO AIR!
4. Stimpacks should be considered as a drug and be illegal
5. Vehicles and massive units should be able to squash smaller units in their way