Shows promise.

Don't be discouraged at the number of cons I wrote. I think if you keep going, it will turn out great. I liked the asteroid level, that was a nice touch, but there were some issues. So here are a few of my suggestions:

To me the ship felt underpowered. On the first level you fill the screen with enemies, but then it takes 2 hits (if I am correct) to bring down the fastest smallest ones. This creates a feeling to the player that their ship can't actually handle this and what you should do is just dodge the enemy ships and bullets and forget about shooting them. I would power the guns up about 2x times. So it takes only one shot to kill the weaker enemies, because that's usually how many you get at them before they leave the screen. Also make the weapon sprite for the bullets your ship shoots bigger. This would also lessen the feeling of being underpowered.

Of course it would be great also if you develop some power-ups. Like more bullets for your guns, missiles, shields, cloak, automated turrets on the sides of your ship. Anything like that, try to be as creative and original as possible. Maybe you will come up with something that hasn't been seen in any top-down shooter yet.

The lack of different enemies is probably one thing you will work at even without me saying so, but just in case: The levels got a bit repetitive and boring, I don't know how long you are planning to make them, but something should change every few minutes. Like a new enemy, added powerups, boss comes etc. I did like asteroids level though, your ship feeling weak actually worked well there. It would be absurd if you would escape into an asteroid field and then blast your way through. If you make the guns stronger as I recommended, then also make the asteroids stronger too, for the same balance.

Another slight gameplay tweak would be to change the fire button. I had to read it from your F1. If a gamer starts up a top-down shooter, the first buttons he starts pushing to shoot are space, ctrl and buttons like that. The more intuitive the game is and the less you have to read a manual the better. So I would change the fire button to space.

Last thing would be the graphics. I am not sure if you have tried to or not, but please try to make your own. Or find someone, who will make you some semi-professional looking ones. Players here are tired of seeing those same graphics in every starter shooter.

Remember, you don't have to listen to any of these suggestions, just my thoughts. Wish you luck on your game :)