put yourself on red , and team2 is AI on spot green and yellow ( playing mega ). Now start game with fog of war disabled.
Speed up the game with + key and you will see the units pile up very quick .....
Another hint: Big rocks are much bigger than normal objects on the map. If you use them surround them with unvisible blocker units like I did in the example below. if you don't do so, the units walk into the rock and this doesn't look good.