New WIP build is here: http://graemeborland.com/gamecontent/ludumdare/

The major changes since the last build are:

• Music / SFX! (the song is called Xperia by DIM.M, via jamendo.com
• Increased the size of the play area
• Player ship moves faster now
• Changed colours of enemy death effect so they won’t be mistaken for bullets
• Gameover/title screens

Let me know what you think, I’m going to try to add more varieties of enemies and maybe even some more weapons to make things more interesting. I think the biggest weak point right now is that the waves of enemies are all very similar.