I found this extremely difficult. Interesting idea but I think it needs more build-up or tutorial (I know, game jam time limitations). But maybe even having it start out with more focused waves of bullets instead of jumping right in to having them come from lots of directions at once? Since Godot lets you animate any property, my brother has used animations with tracks for things like particle spread and direction, emitter position, and so on. That technique makes it really easy to build a difficulty progression over time.
I think two sets of left/right keys (like A/D for one shield and left/right for the other) might have worked better for me than trying to do it all with one hand (left/right up/down) the way it is now? I had trouble with the up/down for rotation.
Sometimes the red dots went straight through the shields. I'm not sure if that was intentional or just Godot's buggy physics, but it was confusing.
Nice concept though. I'll have to come back to it after the rating period when I have more time to practice the mechanics.
And (blatant plug): our game is Filament (https://itch.io/jam/gmtk-2019/rate/460871) if you want to try another probably-accidentally-way-too-hard-jam-game. :)