I've pretty much finished my entry, called Deep Sea Encounters.  I'm pretty happy with the way it turned out, as with all these things there's stuff I could do better but time and budget unfortunately make it the way it is.  Stuff I would have changed - 

Proper 3d graphics instead of 2d

Custom art and sounds instead of random stuff thrown together.

Maybe the gameplay could be tweaked to add different kinds of shields and attachments, giving it more replayability.

The stuff I struggled with is the timing for the attack patterns.  It seems so easy but it did take a while to get right.  Particularly the bosses, it took me quite a few iterations to get the firing working the way I wanted.  I learned a lot about shaders during this development and I'm glad I've participated as I think the pressure to actually produce something is probably more like a gaming development environment, rather than just tinkering with stuff for my own amusement.

Thanks for playing the game everyone and all your positive comments, I've released version 1.1 which is a much easier game.  I've basically put a difficulty multiplier in and whenever an enemy shoots the timer is multiplied by the difficulty (so they fire much less often).  I've also multiplied the player's shield strength by the multiplier.

Good luck defeating the last boss I know you can do it!

Rick.