in game: send: press send to send the vectroids. the goal is to kill them all before they reach the end of the path. auto: press auto to automatically send new vectroids every level towers: place towers alongside the path to attack the vectroids. green towers give bonus damage to green vectroids, but give reduced damage to red vectroids. red towers give bonus damage to red vectroids, but give reduced damage to green vectroids. purple towers give bonus damage to purple vectroids, but give reduced damage to blue vectroids. blue towers give bonus damage to blue vectroids, but give reduced damage to purple vectroids. towers in play can be sold for 80% of their value. towers in play can be upgraded for 50% of their initial purchase cost. when upgraded their range and damage increases. bank: your current money. gain money by killing vectroids interest: starting from level 2 you gain interest over the money you have in the bank when you send in a new wave of vectroids. example: your interest is 5% -> you have $1000 -> you press send -> you gain $50 with this said is it always better to first send the vectroids to collect interest, and only then start building towers. next: in the rightbottom of the screen you see which vectroids will come next, their hp and how much money you gain when killing them. bonus: when gaining a bonus you unlock 3 special towers: power booster: place this near your towers to boost their damage by 25% range booster: place this near your towers to boost their range by 25% interest booster: increase your interest by 5% At the end of each world you take 1/8 of your total worth to the next world. Your total worth is you current money + value of all your towers.