IF you build a wall of suply depots (in your only entrance) Build two Bunkers behind them.
This will work for zerglings, zand zeolts becuase there attacks are not ranged and the can't get to the bunkers.
This is usless agianst hydras and other units with ranged attacks.
If you need more help, we've got more Starcraft cheats and also check out all of the answers for this game
Comments for this hint