People are really hung up about that time travel huh?
I'm assuming all it means is that you will see cave man zombies riding (inaccurately I know) dinosaurs instead of foot ball guys. Or they will have laser blasters that they accidentally shoot themselves with 20% of the time. Or plants that are extinct, or bizarre ones not yet real.
Zombies riding chariots, zombie catapults, Back to the Future hover boards, UFO attacks, reverse pod people where your plants become zombies, zombies armed with shrink rays, teleporters, zomborgs, zombie pirates, samurai zombies....seriously you can go on all night with this stuff.
Releasing it on IOS devices is fine. ONLY releasing it on said devices for the foreseeable future is obtuse.
I got the original on my PS3, and if I had any money atm I'd get it again on my 3DS since I don't have a working TV.
The free to play model though does fit my budget obviously.