Potential ....

This has the potential to be a truly great game ...

Some things I recommend working on:

First off ... work on your movement controls. It was mentioned that this is a somewhat overdone style of game ... the thing your lacking is the front/back movement instead of just the up/down movement. It add a bit more strategy into the game.

I think the idea of adding an upgrade system of some sort is fantastic. New weapons, speed/weapon speed upgrades, engine upgrades, force field, etc ... There's a whole range of things you can do with the addition of an upgrade system.

You animation wasn't bad at all ... but perhaps add a bit more depth to some of your ships? More logo's or a better alien inside the cockpit ... that's more nit picky than anything, but it could improve the overall game quality.

I'd personally suggest putting together a storyline of somesort. WHY are these aliens invading? Is this some kind of a Earth Hero defending against them? Does he have friends? Is he doing this out of a secret garage/hideout? YOu can do so much with a game by adding in a storyline/plot. Break up the game into missions ... give the player a GOAL in the game instead of endless/mindless alien killing until you eventually take so many hits you blow up.

Perhaps add more of a purpose behind the lightning/energy than point increases? Maybe your ship's batteries need outside powering and you have to capture those energy cells to stay aloft? Perhaps each energy cell gives a boost to your speed or your rate of fire?

I think the previous mention of adding a real soundtrack to the game is a mentionable one. Many games get great reviews on excellent soundtrack alone ... you've got more going for you, but it's a start!

Great start, don't stop now .... but I'd definitely recommend doing some upgrades to what you've put together so far, just to make it that much better.

Good first steps (second?) but needs a little work

Its a good game, but first of all it needs music. It doesn't have to be your own, or something made by your friend, but just look on the audio portal one day and find something you like. Secondly, if you plan to make a new version of this game in the future, try to add a little mobility and mabye powerups or another weapons system to prevent the game from going stale. I would suggest a twist, like enemies that fight another group of enemies and you, challenges that give you extra money for some kind of upgrade system or mabye a system that gives you new abilities and attacks as you gain points, I could really keep on going, but the point is, the art is good, the concept is a little overdone but good, and the gameplay needs more work. But anyway nice work, and I hope I see more of it.