Honestly you could kinda describe Plague Inc. as an incremental, at the end of the day you are trying to "increase the number", in this case of infected and then dead people, and you use upgrades to do so faster.
I was thinking maybe the fact that the number can't increase indefinitely would mean it's not an incremental? Maybe Incremental-lite (like when differentiating roguelikes and roguelites, which arguably is a whole can of worms by itself)