Here some suggestions for updates^^
.) add a "fast-forward-button",
it could make the game much more enjoyable ^^ particulary in the first levels, where not much is to do.
.) more reinforcements.
two soldiers are not much and too few in the later levels. Maybe ypu could add an additional soldier with one of the upgrades, like the "legionnaires" or the "warriors"
.) saily age
the upgrade "saily age", for marksman towers is useless in my opinion. I doubt someone would really sell such a tower cause they're are very important, especially when upgraded to "Rangers Hideout".
.) equal costs
the towers should have equally costs or at least nearls equally costs. I think it's impossible to say this one is better so it needs more gold to be built, every tower has it's unique strenghs and weaknesses which has to be calculated for the strategy.
.) more stars.
The stars are indeed very important for advancing, but the bonus levels can become very tiresome.
.) magical-area-of-effect.
There should be some kind of AOE-Damage for mage towers. I noticed that in the later levels there are many armored enemies that could be better dealt with, when one of the mage towers (maybe the sorcerer mage tower). Or the tesla tower could make a little magical damage (would fit for the electrical damage).
.) endless wave mode.
That would be really funny i think
it could be added after finishing the game, with every level and the maximum level avaiable for every level ^^
here some ideas for the expansion
.) Heroes
That would be a cool new feature i think
heroes that can be placed on the paths like the reinforcements with upgradeable abilities. if they die, they respawn after a period of time.
.) super-level
A new level for every tower would be, in my opinion an appropiate upgrade for an expansion pack. This new level should increase damage and/or range and could ulock one new ability for every new tower.
my ideas for this new abilities ^^
rangers hideout: elvish eagle
an eagle with an ralley-point works as a soldier for flying units, blocking them in their way. (upgrades could add more eagles)
musketeer tower:blindinggrenades
throwing area damaging grenades in a very short range that reduces the magical armor of enemies
holy order: barrier
paladins can summon a barrier that prevents enemies from advancing and protects them from damage.
barbarian hall: revenge
when a barbarian is killed, the remaining barbarians getting increased attack speed
arcane wizard: pest
an enemy is enchantet with a curse that reduces it's lifepoints continuous for a long period of time (maybe it could spread on nearby enemies). Pest adds with poison
sorcerer mage: meteor
casts one meteor (like one in the meteor storm spell) in a wide range.
500mm big bertha: nuke
i know, it's obvious ^^ big bertha fires a nuke on the battlefield with big and wide area damage.
teslax104: lightning strike
calls a bolt of lightning on the battlefield whic does damage and a little area damage.
.) money maker tower
a new kind of tower that's only purpose is to create money over time.
these are my ideas for the game and the expansion
i want to express a big praise for your idea to add repairable buildings and the extras like the sasquash ^^
these are really really great ideas