IDW may be one of the Big Five publishers in the direct market — that is, one of the five publishers whose titles are listed separately from those of the hoi polloi in Diamond Comic Distributors’ Previews catalog. But unlike the Biggest Two, IDW’s line consists mainly of comics based on a variety of licensed concepts*, and therefore do not feature shared settings like the DC Universe or the Marvel Universe.
You’d think that would prohibit the company from doing the sorts of line-wide crossover stories that DC and Marvel have been pumping out with regularity, but IDW has found a pretty clever way to have its licensed comics cake and eat its intra-company crossovers as well, by dreaming up a fairly generic threat, and then having that threat appear in a bunch of unrelated comics whose characters never really meet.
Rather than all the characters teaming up to fight the same threat on the same battlefield at the same time, as in your Crisis on Infinite Earths or Civil War or whatnot, IDW’s crossovers are a bit more like individual battles in large-scale wars taking place in different dimensions.
So, for example, 2011′s Infestation crossover pitted zombies from the publisher’s Zombies Vs. Robots comics against characters from G.I. Joe, Transformers, The Ghostbusters and Star Trek, in two-issue miniseries set in different universes. That was followed by Infestation 2, in which Lovecraftian space-god-monster-things invaded the home universes of G.I. Joe, Transformers, Dungeons & Dragons, Teenage Mutant Ninja Turtles and 30 Days of Night.
More recently, IDW published a much smaller-scale, simpler crossover story of sorts in Mars Attacks …, in which the little green skull-faced men of the 1960s Topps collectible cards (and 1996 Tim Burton movie) “invaded” comics featuring a comically diverse group of licensed characters. For the more patient among us, it arrived in trade format this month, in a collection titled Mars Attacks IDW.