for some reason its an adicting game but theres no noticable affect when u upgrade things when i upgraded the size of the bomb it looked like it was the same size. same thing with the size of the parisite so if u make a 2nd heres some sucgestons:
1.make the upgrades more noticalbe
2.add little tentical things hanging off it(to make it look more like a parisite)
3.add white blood cells to avoid there always in the blood with or without anti-bodys.
4.make it look more like a vein make it red or some other coler then light ble.