Might want to put a short invincibility frame in there re-spawning into bullets or enemies and game over isn't fun. Over all a fun simple game tho.

I bought all the power ups in a relatively short span of time. My plan of attack was to keep the ship at the bottom of the screen (except to pick up life, weapon change, money, etc.), keep the ship moving back and forth and spam the air with bullets. Try to stay out of their way and don't get hit by anything.

The yellow aliens (looked like ticks) with red bullets (looked like blood) were the hardest to kill. I just gave up on them and stayed out of their way. Some of the ships were next to impossible, too.

The only big problem I saw was the stuff the aliens dropped when killed were hard to see. They need to be either a different color from the background or darker blue. A lot of them The ones killed off screen didn't drop anything, at least the drops didn't make it on the screen.

I don't know what my final score was, I was too busy trying not to get killed. At one point, I had 503,600+. Next time I was able to check, I had well over one million and that was just before the final boss.

Suggestions:
1). Make the drops more visual
2). Have a better climatic ending
3). Let the players view their scores between waves. Instead of closing the doors and starting the next wave right away, go to another screen and let the player decide when to start the battle. There needs to be a break someplace (after all the power ups are bought) to tend to Mother Nature, answer the doorbell, let the dog out/in, etc. Get my gist?

Tweak it a bit more and I'll give the game a higher rating. It has potential.

Giving it a 3 mainly due to a lot of balance issues.

Enemies drop 0 cash, the end game is meh. The Cash power up is nice to get because it's the one thing that you can count on to give you SOMETHING.

Enemies vs you
They have a crap load of HP, you have nothing...Kinda standardish but the issue then brings me to the next point.

Weapons
These are bad...They are underpowered, over priced and hell unless you have the last upgrades on everything i'm guessing you can't kill the boss? Because I made it to him and I was doing nothing...Not a single damage so...Kinda not balanced. They lack power especially due to the cost of them, seeing as I can barley make 1-2k after 3-4 levels

Controls
Nothing to complain about here pretty basic.

Music/Sound Effects
Not to bad, could use a few more tracks perhaps but it's still solid over all, same with the sound effects they are also solid enough.

Over all the issues come down to
Enemies compared to you are OP
They drop not enough cash to upgrade requiring massive re-play to even be able to compete.
Weapons are horribly under powered.

The art and music are really nice, and the game moves very fluidly. However, the player fires too slowly, and it quickly becomes hard to keep up with all the enemies. I wasn't able to afford any of the power ups, and it got to the point where I couldn't kill any of the enemies before they left the screen. Could definitely benefit from some additional balancing.