Planet Hulk was a run of the Incredible Hulk comic where the titular character was shot off into space by a group of civic-minded superheroes: Iron Man, Mr. Fantastic, Dr. Strange, etc). He lands on a far-off planet, is forced into gladiatorial games, leads a revolt, etc. There are some references to the broader Marvel universe—his misfit band of rebels includes a Brood, for example—but in general it's a stand-alone space opera, with both adventure and some dark and serious reflections.
And then, in just the kind of move that generally keeps me from reading Marvel and DC superhero comics, there's an abrupt and contrived ending that sends the Hulk back to Earth to exact his revenge on the superheroes who exiled him. World War Hulk is one of those grand multi-title cross-over events that just always fall flat for me. These stories always set out to be grand and world-changing, but of course the world can't change too much, because then how would we keep all our 70 different titles chugging along with their endless stories. Blegh.
FuzzyCo grade: PH - B+, WWH - D