The Starcraft Command | home
This is a great rush! When I use to play ladder games I use to go for this almost every time. A lot of the times I won too. Then the slowed the Spire build, but it is still fast enough for this to be a great strategy. Here is the build order:
Take your first 4 drones and put them onto seperate mineral patches. Begin scouting with your Overlord. Then build drones until you have 7. After the 7th build an overlord. When your overlord is done scount with him also unless you have already found your opponent. After that build 2 more drones. When the 8th drone hatches build an Extractor with it. With your 9th drone put it on a mineral patch. (Your counter is now at 8 because you built an Extractor). Then build another drone and build a Spawning Pool with it. When the Extractor is done pull off 2 drones from your minerals and begin harvesting gas. Produce 2 more drones and put them on gas. Then produce 4 more Drones and put them all on minerals. When your Spawning Pool finshes (it should occur befor you build your 11th or 12th drone) immediately upgrade to a Lair at your Hatchery. When you get 300 minerals build another hatchery (it should be around when you build your 13th or 14th drone). When the Lair is done build a Spire. Then make 2 more overlords. Make 2 more drones and have them mine minerals. As soon as the Spire is done building you should have 700+ minerals and 600+ vespene gas, and produce 6 Mutalisks. When you get 100 minerals and 100 gas produce 1 more Mutalisk which makes 7 Mutalisks. Then when your Mutalisks are done you should already where your opponent is from your scouting and go kill him.
The only problem with this strategy is that you are very vulnerable to an attack in the beginning. But when your Mutalisks are done you should be fine.