Orders of BattleEdit
Expect the opposing zerg to be utilizing the same orders as you!
Zerg vs. zerg is the fastest matchup in the game, and goes fairly quickly. Matches rarely take more then 6-9 minutes, so there is hardly a late game and a pretty consistent midgame. The game revolves around the air/ground trade-off – zerglings are cheap and fast to make, mutalisks can kill zerglings. Whoever gets mutalisks alone will be able to decimate the opponent's economy, so the game revolves around trying to get more mutalisks before the other player OR getting mass zerglings before the other player gets mutalisks.
Interestingly, zerg vs. zerg is the only matchup that plays like this specifically because terran and protoss don't have an effective air-to-all attack unit. The Wraith, while it can attack ground, is more expensive and is not strong enough to take on missile turrets. It's also significantly less effective at killing workers, particularly since SCVs can repair.
9 drones, to spawning pool, to overlord, to 6 lings. Counters Overpool
9 drones, to overlord, to spawning pool. Then 6 lings. Counters 12 hatch
Fast Gas OverpoolEdit
Get a second gas to reach mutalisks faster. Counters 9 pool. Mass zerglings.
Get a spawning pool made quickly then send a drone into the enemy creep to take them out early in the game
While potentially effective, not seen often in pro play.
Mutalisks in large numbers, mixed with scourge to kill other mutalisks. The key is to out macro and micro your opponent's mutalisks to dominate the air.
Requiring an unusual evolution chamber, spore colonies are usually a last resort when you can't compete on mutalisks. Since they can't usually cover all your bases, cost your economy heavily (in a drone and minerals), are completely vulnerable to zerglings, and mutalisk micro can pick them off in areas less then 3, they are a desperate choice. But if you can get enough of them while staying economically competitive they can sometimes claw you back into the game.