Hello thanks for playing, there are differents boss items actually, the first boss can give you a life stealer shoot (accumulate energy that restore your life), two differents splitters, one split in thre shooot on impac and another one split in 8 mini shoot when explode.
Also in the second boss there is a chance to get a poison shoot and some shields that can repel or poison the enemies x3
There are many weapons but is luck, like The Binding of Isaac game i got inspired
Level 6, yeah its a little hard, i always do have like that, harder xd, if you get good stats it got easier, and there are 30 level in this demo game