In Starcraft Broodwar we know that using Overlords for dropping Zergling sagainst enemy is a strong tactic.Now we think about orientation of this tactic into Starcraft 2.How can it be possible?Yes,the nature of the Zerg is deeply releated to Overlords which makes this race a dropper race because of its low face to face combat capability the gamers are frequently uses Zerg as a behind striker race.At Zergling drop tactic the last upgrade of Zerglings at the advanced technological ages of the game is superior against buildings and lots of units which makes them a really killer,dreaded swarm.But in Starcraft 2 this upgrade can be compansated by Protoss which have new charge abilitied Zealots.And may be compansated by Terran equipped by reapers Thors vikings.The time will give the answer.