Two Worlds Ninja

Puzzle platformer game.
Control two ninjas from different worlds to grab the scroll.
Still under development, 6 levels for now. Pls give me your advice to help me improve it, thx.
_____________________________
2014.6.1
Lv 8 added
_____________________________
2014.5.31 update:
Level 7 added. Instructions can be found in game.