its nice to have another game in this series, and having the new thing of enemies not just being above is a nice change. I do have a few small problems/suggestions for this. First, with the controls some small details I think the 3rd control scheme should be the default, since everyone seems to prefer that, and also having some more options for the other ones might make them actually useful.
Since its a prototype, these things are fine but I think it would be nice to have some boss fights and other characters and Its too slow at the start. It would also be nice to have something like the survival mode from the first bullet heaven. new backgrounds would be good for turning this in a full game, but since its a beta backgrounds aren't that important. This might just be my preference, but I would prefer the levels to be shorter and more intense.
Overall, its still a nice game, and I think the full thing will be very good.