This tower defense idea was submitted by kris.

A spawn tower - which allows you to spawn creachers to attack the oncomming creachers

Tower stats upgrade - instead of just upgrade tower i think it would be alot better upgrading individual things on the tower…so on each tower you can upgrade..Defence, Power, Speed, Enemies per shot..

Unlockables - Way more things to unlock, after so many kills a new tower or somthing should be unlocked.

Traps, should be able to lay out traps on the path eg..nets

Better upgrades for your Castle or base there attacking….aswell as putting towers with lazers along the path y not on the actual castle aswell..would be cool if you could attach a HUGE lazer ontop of your castle…like seperate guns which can ONLY be used on the caslte.

Foe>friend tower - How about a tower that when it zaps the enemy they change direction and attacks its own troops..maybe your only allowed to build 1 or 2 of these maximum and they zap at a very slow rate and very expensive to build.

Build ontop of towers - if you build a tower..say you build an ice tower for example…how about you can stack a tower ontop of a tower…make a taller tower..only stack 2 or 3 max…but you could have a tower where bottom half is ice tower middle fire tower then top ice tower again..or w/e.

Speed up button - Sometimes youve killed everything and your waiting ages for the next enemies to be where you want them…so a speed up button could be very usefull.