[Blue Tower] Shooting tower, Cost 100
[Green Tower] Slime pit, Cost 150, must be placed in road not in grass
[Yellow Tower] Sniper tower, Cost 200, shoots long range piercing bullet
[Red Tower] Rocket tower, Cost 250, shoots aoe explosive attack.
 Select Tower. Keep hitting  to go through all tower options.
 Upgrade tower. Select upgrades by hitting  then click on a tower to spend 250 to upgrade it.