Wow, there are only a few good things to say about the game itself. You, however, have potential as a game developer.
----Concept & Game mechanics----
First off, let's talk about the concept behind the game. We have our ordinary Tower defense, nothing new here. Next to that, we have the Missile defense. These two are linked in two fashions; economy and loss condition.
The Missile Defense
In the first 2 minutes I went "hmkay, seems fun"; after that I went to "hmkay, you're boring, but the fact that I have to pay attention to you makes you annoying." This is because the missiles just stop becoming stronger, and the upgrades stop doing anything. In other words, there was no progression. The fact that it is tied to the rest of the game so strongly and continuously, makes the game worse rather than better.
A better option perhaps would be to have the missiles come in waves, and to have the turret be upgradeable with money. Besides that, money is not earned only by missiles.
This gives players a time of rest to make decisions, for example which tower to upgrade/build. Second, you give the player a new problem he must solve: where is he going to spend his money, missile defense or tower defense?
It also allows you to make the game significantly harder: as you now can choose what to upgrade, and the player being less stressed with the pure impossibility of playing two games at the exact same moment, you can make missiles waves harder. This means the player now has to rely on his skill of knocking missiles out of the sky.
The Tower Defense
Oh boy. This tower defense is just bland. There's nothing more to it. Now I know that using someone else his idea's is what you want to do, but a lot of idea's become so fundamental that if you do not offer a replacement or compensation, you have to use them to make a fun game.
Here are some things that I miss in this game:
Difference in towers (we have 6 damage towers, 1 poison tower, and 1 tower which I assume is splash?)
Different maps
Diversity in enemies (there are more factors to an enemy than just speed and health.)
Interesting economy concepts
Interesting upgrade schemes
Global upgrades
Now a nice enemy to add for instance would be a mobile missile launcher. It walks across the map, and fires missiles every few seconds that pop up on the missile defense. If you don't kill em fast enough, there will be too many missiles to defend against.
----Graphics----
The basic sprite/artwork seems all right, lacks a unique style, but that's ok. The transition of missiles when hit was ugly and the fact they get reduced to a rocket a stage lower feels extremely unrealistic; maybe design them in such a way that you basically knock off a piece everytime it's hit.
Explosions could be better and a death animation wouldn't hurt either. Missile Defense turret is not in sync with the bullet it shoots. Turrets themselves have a bit weird artwork, random spikes being the entire core of the turret is not a good idea.
There are next to no real animations.
Also there was a specific type of tank that moved in reverse as soon as it went horizontal, that shouldn't have gone through testing.
----Music----
Music is nice, good pick. The Missile Defense turret's shooting sound is annoying, as you cannot stop shooting.
Practical things:
The turret upgrading makes towers seem more alike to each other instead of differentiating them. The three most expensive turrets besides the splash turret are IDENTICAL when upgraded three times.
Tower AI can be improved.
Descriptions of towers need to be added.
Costs of upgrades feel random.
Wave system is nearly unnoticable.
Challenge is non-existant.
Now I like your idea. The way you executed it shows you are a beginning game artist with potential. You need to learn that every detail needs to be carefully thought about. When you've got that covered, you can start making the game. Improve yourself, and I'm sure we'll see a big game coming from you.
Good luck my friend!
