Challenges
Challenge mode pits gamers against each other on world wide leaderboards, awarding trophies and lums for the best scores.
Challenges for the game released so far have included collecting a certian number of lums within a time limit or reaching a distance on a map without dying (normally with a wall of fire or spikes chasing you). Depending on the criteria for the challenge, you will then be ranked against people on world leaderboards and awarded medals - platinum, gold, silver and bronze. Based on your trophy you'll get Lums as a reward (more for gold, less for bronze). Trophies also count towards your Awesomeness Rating, to reach the highest rating of 11, it is a requirement to earn trophies in challenge mode.
New challenges are added both daily and weekly. To gain access to challenges you have to first gain an awesomeness rating. You can increase your awesomeness rating by gaining more trophies in the main game levels.
There are 4 distinct brackets for challenge mode:
Daily
Weekly
Daily Extreme (unlocked at Awesomeness rating 5)
Weekly Extreme (unlocked at Awesomeness rating 7)
It's worth considering that the brackets for gold and silver might change as more people take the challenge and push the averages up. Keeping gold on a weekly challenge might be harder than on a daily because other competitors have more time to take part and perfect their score.