Everyone loves bullet hell shooters!
Maybe it's because I have a soft spot for bullet hell shooters (especially ones that have millions of lollis in them), but this game is great.
The problem is, this game would be amazing, if it were just longer. I don't know if I missed anything or not, but I could only enter one segment. This game that you have gave us seems like a practice stage for one of your stages for the real game. And another thing. Since this is a bullet hell shooter you should put in a practice mode. I know arcade shooters don't do that, but this isn't an arcade shooter. Most people probably don't have the skill to just go through a bullet hell as they would a normal shooter. Along with adding a practice mode, you should add difficulties as well. Why? Look above.
Now from the segment that I played, everything was fantastic. The visuals were amazing, the difficulty was solid, the music was great, and the controls were fluid. You got that down. You even have the SLAVE system good too. It could have been better, like as you progress you get more SLAVE formations, and you could choose which you want to use, or having power ups/upgrades. I would rather choose the latter (second) choice, as having only these two formations add difficulty.
Overall this could be a great game, but it's not, as it seems like only a single stage was made. If you added more depth, like some storyline, and more segments, and improve the things I stated above, then this would be an amazing game. Also, you might want to add a control configuration, because I would prefer pressing SHIFT than X (silly IN Remi).