I have to contradict your point, while it would be valid on most game, this one has a system that allows a heavy reuse of already made drawings, while there is still some art involved, it is nowhere near the amount of art a normal 2DCG game requires, unless the dev decides to create multiple animations for different body proportions in order to facilitate more characters, or is remaking a singiffincant amount of the old art he is probably not drawing all that much. He could in theory add a bunch on new scenes every update, which would just be the same animations but applied to a different character that hasn't had that scene already.