I really like the game and concept. I like the way the energy system also applies to enemies. There's a few things holding this game back, though.

On the plus side, you can hold the button to fire. No autofire though.

• I really wish there was some indication on how much energy you lose for getting hit and for special attacks.
• Energy pickups should fly toward the left, not in all directions and especially not toward the top/bottom edge of the screen.
• Dark red energy blasts from enemies are hard to see on a dark grey background.
• The ability to see the upgrade screen between missions might be nice.
• A damage upgrade.
• A magnet upgrade (matches point 2).

I'm going to need a explanation on what Recovery does too. It seems to expend a lot of energy for nothing.

• You lose 25 energy for getting hit, and I don't think there are any upgrades to change that. It'd probably be better to say that somewhere, but my thinking was people will be able to watch their energy and see the numbers change to figure out how much is lost. Similarly for special attacks. The fireball costs 5 energy (3 upgraded) and the beam costs 2 energy (1 upgraded.)
• Energy pickups fly in the direction the enemy was moving in when you killed them. This is on purpose to force the player to optimize when to kill certain enemy formations to get the most energy back. You can just hold down the fire button and destroy everything in your path, but it will lead to less energy than planning things out. Penny explains this in the tutorial level, although it's very possible it wasn't made clear enough.
• I changed the red fireball outline to a much brighter color to hopefully help with this issue. That change will be included in the next bugfix version which should drop in a few days.
• I agree this would be a nice change, although it would probably take some more re-tooling than I'm planning to do at this stage. Definitely something to keep in mind for the next game, though!
• There are a few upgrades which are essentially damage upgrades. The faster fire rate on your normal weapon increases the amount of damage you can dish out by quite a bit, and the increased beam efficiency is a must-get. Early on the beam does good damage, but is relatively expensive per shot which limits how much you can use it. When it's cheaper, you can fire double the amount of shots as before and rack up crazy damage.
• A magnet upgrade is definitely an interesting idea, I hadn't thought of that! I'm not really planning to add more content to the game from here on out, just fix bugs, but if I feel enterprising I might give that a go as it's a very neat concept.
• Recovery takes an initial startup cost, then regenerates energy as you hold down the button, but you can't move while it's active. At the outset, it's a mediocre ability as the startup cost is high and the regen speed is slow, so unless you use it in a safe place you'll need to cancel it to get out of danger before you've even recovered your startup cost. Once you unlock the upgrades for it, though, it becomes very strong as it has a fairly low startup cost and a quick regen speed.