Complete the required tasks to unlock each Achievement and XP.
Chocolate is the premium currency used to purchase new Forrests (Runner Forrest and Football Forrest) and stages.
Helmets are can be equipped while running, but disappear after use. After buying one for 1,000 coins from the "Helmets" menu, you must also purchase any items that particular helmet requires.
The multiplier increases your speed, allowing you to cover a lot more yards in the same amount of time.
The best way to get around obstacles is to swipe to the left or right of them. You can also swipe up to have Forrest will jump, or swipe down to make him slide. Forrest can roll by swiping up and then swiping down while he is in mid-air. You can also swipe left or right while he is in mid-air to help avoid obstacles.