Everyone knows achievements. You do an in game action, the bottom of the screen pops and “Achievement Unlocked” appears. In standard achievements the player receives a few points which add to an overall score showing the world that they are really good at video games.
Then the mobile version appeared. Here instead of giving the player points they could complete different tiers of achievements and get more direct and usable rewards, like currency. Upon completion of the tier players could go to the achievements page and accept their reward.
In Destiny this has been taken to a new level. When someone completes an in game achievement (in their game it's called Grimoire) they receive a few points. They also receive a card which has a nugget of story or info on something in the game (Something fun to further reward the player and keep them engaged). But they take it a step further. After completing certain tiers, the player will gain better bonuses throughout the game.
For example: If the player kills X enemies and achieves Tier 1 they receive a few Grimoire points and some lore/info. But at Tier 2 They receive a bonus to the currency they receive from defeating the enemy type. (In the game type Grimoire this is replaced by better items dropping, currency payout is for the enemy type Grimoire.)
I believe we can learn from Destiny and apply this concept to mobile. The simplest way I could think of is increase payouts with tier 2. I know many mobile games pay out coins after doing actions. (outside of achievements) How awesome would it be if players were rewarded continually for playing your game? Not just a one-time toast. Or a bunch of free coins. But the ability to get paid out at a higher rate. Much like Destiny has done. Then on the post game payout screen we can emphasize the bonus they are receiving so they will continually think about it.
Oh and before I forget, they do one more thing. They make a point to make sure the player knows what bonuses they are closest to completing as well as the ones they have active. Something similar to this is displayed at the bottom of the screen when flipping through parts of the Destiny companion app. (This is the online version, the mobile app has only one column instead of three.) Doing a miniature version of this is not out of the realm of possibility on the post game /payout screen. (Maybe just showing the next closest one to be completed)
This is just one more way we can show players how much we appreciate them and their time.