There's no cutscene after beating Yeti, just some happy faces are drawn on the screen.
Oh come on, Yeti should at least sink through the floor in a chain of explosions. Then, where's Penny? Are we supposed to have saved her? And where's that guy in a spiky helmet who kidnapped Penny?
If we are supposed to play Forest World after the Ice World, defeating Yeti should open Forest World.
Is anyone working on this? I think I can at least implement the 'sinking through the floor' animation.