Schism

Entry for Ludum Dare 51: "Every 10 seconds"

You have picked up a crystal that has cursed you to shift between two different dimensions every 10 seconds. The only way to be free of it is to collect the other three crystals nearby. They only exist in the normal dimension, and are only visible when you are close, but the crystal you hold will ping when you are near another crystal, and will ping faster as you approach it.

While in the dark dimension, everything can hurt you, even the trees. If you are hurt, you will heal (slowly) when back in the normal world.