I dont see the point in buying more expensive weapons. They are not better than the machine gun but just have other strengths/weaknesses. There should be a net improvement when I spent money. Nice idea but needs more work on the weaponary. Also keps lagging when you click outisde the game accidently... One more thing: that risk calculation/limitation makes no sense to me...
I usually don't comment on games. But this one is actually worth to leave a message. I like the idea that you cannot simply spam towers. Instead you really need to carefully time your production schedule. Very nice, very innovative and very addictive. Needs sequels ;-) 5/5