Spikes and snowy top

I decided to add spikes to the game. When the player hits them, they die and spawn at the latest check point. The reason I added them was that previously when the player failed a challenge and fell, they had to climb back up. This seemed frustrating, so now the player gets a merciful death instead and can try again almost instantly. There's also a neat little death animation.

I also added some snow and ice to the top of the mountain.

Cheers!