Really good game :) Graphics is the best part - especially the thing that all object are hanging on rope :D love that idea.
Btw, would recommend to flash the shield lighter / more intense than darker / less intense. When you flash shield on lower intensity, it feels like the shield is getting weaker. If you wanna tell player "there is shield, there is no point to attack at this object", it's better to flash that shield stronger, to let player know "this shield is really strong" :)