Okay I pushed out a update version 15: that removed all push block puzzle cubes and kept only the speical ones meant to kill enemies; this included a lot of level design reworking to get right as the movement boku has to do to get to each speical puzzle cube is more complex and more so the puzzle itself than pushing blocks out of the way now. Every level in the demo was redesigned around this.
The boss and its core programming along with the level was redesigned so in a similar way you get to a special sword puzzle cube then cut down the boss until it is dead.
I highly recommend playing version 15 as it is based on your feedback.