Actually this has some great potential, but its got too many flaws.
The music is a bit repettitive. The graphics are actually pretty nice. The problem is that the progression is extreemly limited. Enemies eventually spawn in at a rate that you don't have enough energy for. Once you hit he point where using the primary attack cant cope, you switch to the narwall power. And then you eventually run out of energy.
How to make this better:
You need another set of choices. In a horror game, when you run out of bullets or realize that your weapon is ineffective you turn to stealth or just run away. You use another choice.
The overused idea is an upgrade system. You die and then come back stronger.
Another idea would be having the narwall dive, like hiding under the waves. Makes you invincable, but stops your score from increasing and gives you time to recharge.
Final thoughts:
This is 2 min worth of time and then its done. With a few tweaks I think this could be an hour or two worth of entertainment. For the work thats been put in the pay off seem too little.