QUOTE(westley0214 @ Dec 14 2010, 10:57 AM)
Most of the times Zerg will expand at mineral field. But there are several circumstances where Zerg will put one more hatch at own base.
1) If Zerg's choke point has been blocked by two bunkers (Terran) or two Pylons and a Cannon (Toss) and cannot go out to natural to expand early game, he is forced to hatch at his own base for more unit production.
2) Zerg wants to have rapid map control i.e. more creep spread without using a lot of Queen's creep tumor.
3) The hatch at own base is easier to defend against opponent's aggression.
But mostly it's because of the unit production part.
the main reason for an extra hatch is for more larvae to dump ur minerals or to make units in general...
you would rarely see this in 1v1 unless the zerg is on at least 2 base (i follow the general rule of 4 hatches on 3 base, 3 hatches on 2 base if i mutaling)...
or when u have more income than u have the larvae to spend on (i'll drop an extra hatch when i see my mineral shot up to 1.4k or so)
for 2v2/ 3v3/ 4v4 its very common for rush strategies as the extra larvae allow u to reinforce with speedling faster where its common to put early pressure/ rushes...
This post has been edited by evofantasy: Dec 14 2010, 11:39 AM