Waves 1 - 10
– Focus initially on upgrading the top towers then place a Gun Tower on the north-eastern corner of the central bridge.
– Set a Gun Tower in between the left towers and the bridge (this’ll help catch any helicopters and will also target the runners above).
– Now place another three Gun Towers south of the bridge (as per the screenshot above) and setting down a Slow Tower north-west of the bridge will help with the runners and the helicopters.
Waves 11 - 20
– Block off the top exit and create a funnel of Gun Towers left, block off the right-hand entrance so they’re all heading towards the bridge.
– Set down a Spark Tower beside the Slow Tower (but leading to the entrance of the bridge itself).
Waves 21 - 30
– Focus on saving up enough cash to buy a couple of Tesla Towers and place then at the right-end of the bridge. These will not only damage any units that run past, but also take good care of all flying units.
– Get another Spark Tower on the outside of the bridge (see screenshot above).
Waves 31 - 40
– Drop four turrets down near the bottom-left corner of the screen (in a diagonal then a straight line).
– Place a Tesla and Slow Tower at the end of the bridge loop and set a few Gun Towers so they’re leading to the north end of the map.
Waves 41 - 50
– This time, focus on placing towers from the right-hand exit to the bottom exit (in a diagonal line to minimise the number of Gun Towers needed).
– Setting down a Slow Tower by the right-hand exit will give the nearby Tesla Tower more time to finish off any flying units that happen to rush past.
– Swap out the Gun Tower facing the northern entrance with a Flamethrower Tower.
Waves 51 - 60
– Upgrade the northern Flamethrower Tower to level three and set down a Slow Tower in-between the Tesla and Gun Towers at the top of the map.
– Remove one of the left-hand Gun Towers and just above where it was, place a Plasma Tower.
– Set a second Plasma Tower further along to the right (just after where you placed the Slow Tower that’s sitting above the Tesla Tower). This way, they can bounce back off each other as the units are all being slowed down.
Waves 61 - 70
– Now you just want to focus on upgrading the Plasma Towers and sticking a Flamethrower Tower at the starting point of the central bridge.
– Also remember to upgrade all Tesla Towers and feel free to swap out a few Gun Towers for Spark Towers when you’re feeling flush with cash.
– Finally, set down and upgrade a Tesla Tower just opposite the southern exit as a few vertically flying units will make it that far by this point and this’ll finish the job off properly.