Good concept, would have preferred it to be a bit more fast-paced! Some music would also go a long way!

Nice game. I like the idea of having only defensive tools.
A few things I would have made different:
- Reduce the time between enemies. Often I had nothing to do for a long time.
- Was there some kind of time how long the barrier can stay? I saw nothing about it ingame and would have loved an indicator pointing: The Barriers energie (or whatever) is nearly empty! (or something like that)

Also I found a bug, where you can push the cargo carrier with your mouse shield and when you rotate the shield away from the ship, it launches you out of the screen with now way back in :wink:

The whole personal shield mechanic, and positioning your ship to block seemed quite good. The elemental shield mechanic of the carrier however, I didn't have a very good understanding of other than put up the shield when being shot at, and drop it when you're not.

Is the large delay between waves linked to the shield cooldown? Maybe you could immediately drop and refresh the shields once there were no enemy bullets left instead to increase the pace.