You need to change the way experience is distributed and leveling up. At the moment, the front line of defence gets all the experience until you get to a certain point where the front line get swarmed, but because the back line of defence have seen nothing of the enemy they are ridiculously under prepared to deal with the stupidly high powered enemy at that point. Maybe rounding out the experience to be given to each tower would be a better solution.
Akirasan - I didn't realise it was your first game. In that case - well it still needs a lot of work to find the right balance, but it's not bad for a first effort and a lot better than most. Look forward to a seeing a version that is playable, cos once you get the mechanics right this will be a great game.
Challenge is non existent as you just make a logical progression of the lights. Why use up twice as much space as you need to by combining lights and switches. Music is good tho.
ok. Start level 2. Computer Player 2 starts with 45 armies. 29 of them in one country alone. I start with 19 altogether.
Seriously. You need to sort out these random values and balance the game out.