There should be a boss... which is Doborog... which would be amazing.
It would look like the 2d Doborog that is your profile pic and when you start up the game but it would be 3d and would bite, slash you in half with its tail and possibly have laser eyes. The circles on the 2d one could be spheres on the one in game. Possibly could sit down every once and a while to bark which would give you and opportunity to slash at it but its tail could kill you if you go behind him. Or it could be the other way around, maybe when he barks he barks at you which launches you backwards. The doborog would be pretty big but not too big lets say maybe as big as Spidertron-5000.