1. Blue and Red circles open and close bridges.
2. The Number Tile: if it says 5, then you must land on it with 5 bubbles to open a bridge.
3. The Ice Field - there are no individual steps, just gliding to the end.
4. Arrows force movement.
At the moment, I'm stuck on level 55. There are 60 levels. The game is free and there are no ads.