Buy that, and you'll have no problem with the rest of Rampage's plot, which includes a hand-severing space rat, a Ph.D geneticist/ex-con/love interest (Naomie Harris) and Jeffrey Dean Morgan as a government agent with the kind of cranked-to-11 phony southern accent usually only heard when a Connecticut carpetbagger runs for governor of Texas. "This ol' cowboy!" he says of himself. Twice.
George gets mutated thanks to the monster-making green gas owned by evil Energyne CEO Claire Wyden (Malin Akerman bedimmed by a brunette dye job) and her chin-dimpled, doltish brother Brett (the terrifically funny Jake Lacy), who had nearly cured cancer with a gene-altering concoction named CRISPR when Claire realized she'd make more money selling giant killer rats.
Rampage the movie is so oblivious to what made the game fun that Claire could have missed the connection. Rampage was a verb -- you slid into the creatures' skin and personally wrecked Peoria. (And when the soldiers shot you down, you shrunk into a naked human and scurried off the screen.) But director Brad Peyton sides with the guys with guns. He doesn't put us with the behemoths feeling their confusion and rage; we're above them in drones.