Some 5 years ago I created a campaign I boringly named "
Protoss Secret levels" (check thread)
which features this kind of behaviour... but not with overlords... (after all you only need a few to control very large amounts of zerg units i.e 3 overlords are enough to control 12 zerglings and 10 drones since each overlord can control 8 units... if one is killed... c'mon they're under the control of 3 not only one... etc, doesn't make sense unless ALL overlords are killed...)
the fact is that in my missions Zergs go crazy and lose control of their forces once a cerebrate is killed, I know you might be thinking "yeah, nothing new with that"
the case is that they begin to attack random targets(even other zerg that were their allies) so they run amok in utter chaos!!!
if that doesn't sound interesting... then I don't understand you people...