I think that the problem with this one is, even though the new systems are tough, but fun at the same time, it's hard to pass some levels because you keep switching play modes and have to level up by selecting weapon upgrades (which don't help you in the artillery mode) or skills (which aren't as useful in other modes)
Make it so that the waves don't start while you're still trying to kill off the old ones, make it so energy recovers faster at the platform and get rid of the glitch that makes it so you can't buy things. then your game would be pretty good.
So, you should probably limit the number of things that can be on the screen at one time (Projectiles, enemies) and you should also consider making a way to toughen up your ship.
You should probably make the mouse aim and shoot rather then G. When using WASD, G key is a little hard to hit when you're being pushed around by enemies and trying to aim at the same time. Also, enemies can stand in you and be immune while they can still kill you just fine.
It would be nice if it saved your position settings when you lost a level. Also, if the screen was a little bit bigger. Some of your levels have a lot of exploding enemies, antimatter ammo and reduculous conditions with no way to up durability
It could also be a reference to the divine comedy. Vergilus and Dante were the names of two characters in the book Dante's Inferno. Devil May Cry took the concept from there. There's an entire page showing similarities.
I'm sorry, but until you eliminate the levels with upward progresstion that make it oh so easy for an enemy to spawn right on you and knock you to the beginng or turn down the spawn rate, this game is the worst archer game I've played on the site.
LAG
If the game is lagging for you right click the screen, go to settings, and switch the storage amount to unlimited.
Since it's in the description, there's not an excuse that you're whining about it.
As has been pointed out, your angles need some work. Take into account that an object that bounces off a surface should leave at the same angle that it came in.
To be honest, I don't like this game. The lives system is fairly unforgiven considering that to hit half the enemies you need to almost let them kill you.
So, I'm really enjoying this game. I sincerely hope that it doesn't get badges as this will simply encourage players to play with a guide. Thank you for the simple, yet difficult game concept.
So, the whole shooting behind you think kinda sucked, and the kick back made a couple guns a little useless, but I've played the sequels so I know it got fixed. Not a bad game all in all, but..