With the recent update 12 (Changelog) the Rewards Menu got completely reworked.
Every 24 hours, you can claim your Daily Rewards. Make sure to log in every day to maximize your growth!
The timer for the rewards starts the moment you collect the previous reward.
Allows you to farm SP when offline. As of the 0.9 Beta: Final Phase update, the claim cooldown is gone — you can claim your offline rewards immediately when you log in, and double them with a purchase. You still need to play for 15 minutes before being able to collect the rewards. The max amount before you have to claim is 24hrs. It calculates the SP you get based on the highest mob you can one-shot at the rate of 25 mobs per minute. As of Update 22, your equipped weapon's perks (Damage, Penetration, Crit Chance and True Damage) are also factored into the offline kill math, so a perked weapon earns more than a plain one.
Ranks now give rewards! Higher your rank, the better your rewards. You can claim once every 24 hours or everytime you reach the next rank, so don't forget to collect them before you decide to reach the next rank.