Let’s talk about a popular retention mechanic: Energy.
That’s right. Energy is a retention mechanic. It can be used to monetize (and do social stuff), but it’s primarily a retention tool.
Let’s define energy mechanics, just so we’re on the same page. Energy is a time-renewable resource consumed when players initiate a game’s core gameplay loops. It’s a rough definition and needs work, but it suits most of our discussion purposes.
I’ll break this down a little further, to make it clearer. Energy is a resource consumed when players initiate a game’s primary gameplay loops. A game’s core gameplay loop is what people would consider to be the broad actions of playing a game. Planting crops, solving puzzles, launching missions, investigating crime scenes, etc. When a player initiates this, the energy is consumed. Variations do exist, although they are still tied in concept; in Candy Crush Saga, your energy resource (“lives”) are only consumed if you do not successfully complete a puzzle. However, viewed from another angle, one could say that lives are consumed for attempting the puzzle, and your reward for beating it is to have your life refunded.
In any case, should a player exhaust all of their energy, they are unable to initiate the game’s core play loops. They may be able to do other things with the game, but these actions are usually limited to acquiring consumable resources. They cannot gain experience or see new content. The actions that cost energy and the actions that don’t cost energy aren’t decided arbitrarily. This is very deliberate.
Like I mentioned earlier, energy is a retention mechanic. Let’s think about what would happen if players didn’t have energy. They would start a game, and if they liked it, they’d just keep playing and playing. Eventually, they’d hit a point where they were done with all the content in the game. No more quests, no more puzzles, no more reason to keep playing. That’s when they quit. Even if you do have enough content, they can play until they burn themselves out and quit. That’s bad news for a game. A game needs money to live, and players aren’t usually willing to pay money until they’ve been playing for a while. The game needs player to come back every single day, building up a presence in that player’s life, being a constant source of fun and generating a feeling of good will. That’s when a player might decide it’s time to return the favor and give some money to the game.
That’s why energy can run out, but energy doesn’t just bottom out at zero. Energy has a cap; from casual observation, usually five iterations of the core play loop if it isn’t an invest/express game like Farmville, but in general, you get a play time of 15 to 30 minutes out of a full energy bar. I’ll save the talk about the specific numbers for a future talk, but the point is that energy can top out, and time that you spend with a full energy bar is energy that you’re losing by not having enough space in your bar to hold it. That triggers something called loss aversion. People don’t like losing things, and while a player might not literally be losing something here, they’re losing out on gaining energy, and that encourages people to check back throughout the day, see how they’re doing, and burn off some energy. This is something called an appointment mechanic. Appointment mechanics include things like rest XP in World of Warcraft, but it’s something I’ll talk more about later.
Combined, those two are the main point of the energy system. Slow a player down so they don’t see all of a game’s content too quickly. Provide an incentive for them to play the game regularly. It’s both simple and effective. That said, energy can also be used for monetization and acquisition. Many games will allow players to spend money to buy energy. Used carefully, this can generate a lot of money, but you need to be careful of making sure players can’t just burn through all your content. On the other hand, if priced so a player spends more than the expected lifetime value burning through the content, maybe this might work out for you. The fact that practically every game will sell energy for money suggests that it usually works out for the best.
Energy is also used in many games as a social mechanic. You can ask your friends to give energy (or rather, click on a button that causes you to gain energy. They don’t actually lose any of their own). You can give energy to your friends. You can invite friends and get energy for it. You can visit your friends and collect energy. There are lots of ways this can work out, but it all boils down to players asking their friends to sign up and incentivizing them to play the game after they’ve signed up. This results in organic acquisitions, better retention, and an actual community of players who will talk to each other about your game.
It’s easy to see energy as primarily being a monetization mechanic, since players usually only see it as a popup that asks them for money, but its power as a retention tool really can’t be overstated. It’s simple and effective, and it’s no wonder that so many games use it.