The Daily Challenge is a way to earn more nuggets exclusively in the mobile version of Rail Rush.
To win a Daily Challenge and earn a reward, the player must travel for a total distance across multiple runs.
Every time the player starts up the mobile version of the game with an internet connection for the first time in a day, the game will silently download a new Daily Challenge and give the player a free sum of 500 nuggets.
Progress on a Daily Challenge can only be checked after one run is finished, as the Daily Challenge screen shown above can only be accessed from the Reward Screen. The Daily Challenge screen also displays the distance goal and the nugget reward for those who complete it, which change each day.
If the player finishes a Daily Challenge during a run, a notification will appear on the top of the screen and the reward is automatically added to the current run. Once a Daily Challenge is completed, a "COMPLETED" indicator will appear on the Daily Challenge screen and the player must wait for tomorrow to get a new challenge.
Lastly, it is also important to note that Daily Challenges are not called "daily" for nothing, as each Daily Challenge will expire on midnight. If the player does not finish a Daily Challenge before the midnight deadline, that Daily Challenge is lost and the player will have to begin a new Daily Challenge in order to earn more nuggets.
In the mobile version, since it is generally difficult to earn nuggets in several runs, winning Daily Challenges can be an easier way to earn more nuggets, in addition to beating missions.
Using Steam Power boosters can also help the player beat Daily Challenges, but it can be more beneficial to buy the Mega Steam Power at a one-time price and use it in every run.
Players who can afford to buy the 500-meter head start premium power-up for $1.99 will be able to beat Daily Challenges easily by repeating a simple cycle of starting a game (which causes the cart to travel 500 meters) and committing suicide immediately after to reach the goal quickly. Due to this exploit, it can be justified that the head start power-up is an in-app purchase.
The player can repeatedly earn 500 nuggets without playing a game by starting up the game with an internet connection once per day. This can be a slow, but clever way to earn profit, although this does not work as often.