Reward Systems in Crossy Road, Skyward, and Jetpack Joyride

Our next game, Pig Eat Ball, is a grand adventure in the vein of the Mario Galaxy series. But we are also making a new, secret mobile game about which we're very excited! With that in mind, we examine some other mobile game design choices.

A new game called Skyward was released a few days ago. It heavily borrows its aesthetics and Escher-like geometry from another game, Monument Valley, but the gameplay is different. It's an infinite-runner style design, in which you have to climb as high as possible. You control two dots, and each step is scored.

Similarly, Crossy Road is another infinite-runner game in which each forward step is scored as well. And an older, auto-scrolling runner game Jetpack Joyride has you trying to fly as far as possible for the best score.

These games all have different reward systems and I've been considering their differences to look for things I liked.
And while we're at it, Flappy Bird will come up too. It is another infinite-runner. Its score system is based on distance too, but it has no content reward system.

Content Unlocks

Jetpack Joyride is on the content-heavy end of the spectrum. In the game you can collect small coins which you continue to accrue across plays. These are stored and you are able to spend them to  unlock many different pieces of content including: new head art, new body art, new jetpack gameplay, new one-time powerups, and more.

Crossy Road features a coin system also, and you accrue coins across plays. However, there is only one type of content to unlock, which is new characters to use. There are dozens of characters, such as a wizard, a dog, a basketball player and more. While none of the characters modify gameplay, some make different sounds, and some do ancillary things while you progress (for instance the wizard can zap and burn trees and cars around him). For every 100 coins, you get the chance to possibly unlock a new character.

Skwyard measures steps to unlock new content, but the steps do not accrue across plays. Once you hit a new high score, such as 20 steps, 30, 40, etc, a new pattern of gameplay is unlocked. This new pattern will then show up in the gameplay.

Scrolling Content Release System

All of the games use systems in which level/environment content is randomized with each play. The patterns unlocked in Skwyard begin to show up randomly as you play. Crossy Road has a few segments that it interchanges: grass and trees, roads and rails, and water and logs. Jetpack Joyride has a system in which large environment chunks may possibly show up as you play. Players always start out in the lab, but eventually they can encounter a warehouse, a greenhouse, and even an underwater tube. Players do not control this type of content, except through repeated plays.

Additionally, the coins and enemies in Jetpack Joyride have different patterns in which they can appear, and these patterns are randomized during plays, and intermixed with the different environments. Crossy Road randomizes where it places coins, but since they are singular coins there's no new patterns to notice, though the difficulty of coin placement can change. For instance, sometimes a coin can show up on a log, or around a corner.

Monetization

Because it does impact their structures, let's look at monetization briefly.
For Jetpack Joyride, their current system is only through in-app purchases (IAP) of more in-game coins. Players can spend real money to buy coins or grind to get more coins. In either case, they'll spend their in-game coins on new content.

Crossy Road is a blend of IAP and full-screen ads. The ads however are only shown when the player decides to watch them. Players are rewarded with in-game coins. Players can unlock the new characters with real money (directly) or with in-game coins.
Skyward only uses ads. There are fullscreen ads and banner ads. The banner ads run during gameplay and the fullscreen ads run after you die (though not necessarily after every death).
Suggestion: I'd move the banner ads to the top of the screen, not the bottom as it's possible to accidentally click them.

The Player's Mind

Jetpack Joyride is a very content heavy game, with a large store in which to spend in-game coins. 

Skyward and Crossy Road unlock system are similar but also different.  Both have a single content type to unlock (patterns and characters). The important distinction is in Skyward there is only one thing to consider. How far did the player get? The high score is exactly the goal *and* the path to unlock content.

In Crossy Road, the high score is the assumed goal, but the player also gets to consider in the back of their minds, that if they keep collecting coins, they'll get to unlock a new character. The goal to get the high score is open--players are not required to grind to achieve a high score. The grinding is purely player-driven to get a new character, and fortunately the grinding meshes nicely with trying to get further in the game.

Similar to Flappy Bird, in Skyward the singular goal of getting further can be compelling, but I personally find having some other thing on my mind more interesting. By fusing the presumed goal (get high score) and the reward system (high scores unlock content with no carry-over between games), there is only one thing on the player's mind. Get the high score. Whether this is compelling enough for extended play is a matter of personal taste.