You have to solve small puzzle to damage the bosses and this is really cool. Especially the first boss.
Other bosses involve ability o spin around them, that is usually the best way to dodge its bullet or find weakspots, so use of theme is really cool done.
My main issue its that beside first boss, other bosses are all the same, only with more difficult level. There is a lot of them. Maybe creating less bosses, but focuses more love on 2 or 3 of them will results better.
Usually I dont realise when I die. The respawn is soo quick, we spawn almost instant after the death, so it looks more like a teleport. Additionally its difficult to recognize when we receive a damage.
Over all high score from me, so GJ!