I did not understand what gave me the x1.5 modifier, but thought that it might be building in lenghts.. So I build a long tube, but only got to x3.0. Now I'm thinking it has to do with the amount of completely upgraded cells? Maybe I skipped dialog in the beginning haha. I also did not understand how other players can have this many flower fields, as mine always instantly got infected by birds and I had to paya lot to turn them back to flowers. That made me just upgrade all to concrete which is not as fun. Game structurally is very cleanly made though.