Not a defense game. No ads. Otherwise fine.
This is a solid effort from an up-and-coming flash developer. It's not really a defense game. It's more of a side-scrolling shooter with advancement elements taken from MMORPGs. The gameplay works well, mechanically, though there is still room for improvement.
The only real glitch I could see was with the health bar. It was larger than the frame for it and I couldn't die. I assume the health is expressed as an integer, game tried to subtract a higher number from the health than was there, it went lower than zero, and as a result the integer value wrapped around to the highest possible value and now I can't be killed. Try expressing the health as an integer that can include negative numbers, and instead of
if (health==0){ gameOver();)
use
if(health <= 0){ health = 0; gameOver(); }
That should prevent that kind of problem from re-occurring, if it's caused by what I think it is.
Overall, this is a solid early effort. I'd like to see enemies that do different things based on their appearance, difficulty that advances automatically, more stuff going on at once (good things to collect, not just bad things to avoid,) more levels, bosses, and generally more content. Also, it's a good idea not to split up the control between the keyboard and mouse if the keyboard already uses two hands.
This is great for an early game, though. We all start with tutorials. I look forward to seeing what Sparkplug90 brings us in the future as he hones his craft.