Core Game Mechanics

Breaking your game down into it’s core mechanics might be one of the hardest things you do, but it’s worth it.

There isn’t really a recipe for success when it comes to games, but keeping your design focused certainly increases your odds. When making a game it’s very easy to be distracted by parts of the game that aren’t central to the core experience. This is why it’s helpful to identify your game’s core game mechanics in order to focus your design. Whether you have an idea for a great game, or need to fight feature creep in a current project, these exercises will keep you focused.

Goals

In this post we’ll

• Write an essence statment
• Diagram our core game loop
• Identify a game's core mechanics

The result should be a better understanding of the player’s experience which can guide your design decisions resulting in a more focused game.

First, let’s define what makes a core mechanic that way we know what we’ll be working with. In this post I’ll use the definition from the book Game design workshop.

The essence statement

To identify your game’s core mechanic begin by writing a short (one to two sentences) description of what the player does when they play your game. This description will be your game’s essence statment. not only will the game’s essence statment help you to communicate what your game is about, it will also remind you (and your team) why you’re making the game in the first place.

A good essence statement conveys the player’s goal, the actions a player can take, and their role in the game in 1 or 2 sentences. For example, DOOM (2016)’s description reads:

There is no taking cover or stopping to regenerate health as you beat back Hell’s raging demon hordes. Combine your arsenal of futuristic and iconic guns, upgrades, movement and an advanced melee system to knock-down, slash, stomp, crush, and blow apart demons in creative and violent ways.

From this description we know exactly what to expect when we pick up the game.

• We know the goal of the game: "beat[ing] back Hell’s raging demon hordes"
• We know the actions the player can take: "slash, stomp, crush, and blow apart demons" (player actions are usually in the form of verbs.)
• And, we know the player's role: "you" (this implies that it will be a first person perspective as opposed to, say, Resident Evil 4 where players take control of the character Leon Kennedy.

Seems simple, right? Let’s try it out.

For this exercise try not to focus on the game’s art, story, or setting. Instead Focus on the goal, player actions, and role. Take some time to write out your game’s essence statment now.

Done? Beautiful!

Before we move on let’s revisit DOOM’s description to see what else we can learn about the game from the 2 sentences. On top of the roles, goals, and actions in the description we also learn a bit about other mechanics that add to the player’s experience. “There is no taking cover or stopping to regenerate health” highlights two game mechanics that set DOOM apart from other modern shooters. Unlike Call of Duty or Halo, players are encouraged to play aggressively. By eliminating cover players are forced to act ant think quickly. At the same time, the player receives a lot of health by performing melee attacks bringing the focus back to the advanced melee system and player actions of “knock-down, slash, stomp, crush”. Now would be a good time to look back at your essence statment and see if there are any core mechanics that you didn’t mention that you can incorporate in the same way.

Core Game Loop Diagram

Another way to determine what the core mechanics of our game are is to create a Core Game Loop diagram of the game in order to visualize the core gameplay. This diagram shows the series of actions players takes in order to play the game. In other words, what is player doing over and over again? The diagram you come up with is called a core game loop. Diagraming your core game loop is a good way to focus/edit your game and can be shared as a blue print with your team. Your core game loop should also support your game’s essence statement.

Let’s look at a popular game genere and their core game loop to get a feel for them before making our own. RPGS, for example, can be described as a loop that contains the actions Defeat enemies -> Get Reward -> Level up, Repeat. Once your game’s core game loop you can use it to identify and strengthen the core mechanics of your game. Generally, all of your game’s core mechanics should be in service of the core game loop. If one of your game’s mechanics doesn’t support your game’s core game loop, or your essence statement you might consider eliminating it.

The following are some common core game loops and one specific example using the game Pac-Man:

Although the core game loop of your game won’t look exactly like these, they’ll probably look very similar.

You’ll notice that the diagram for Pac-Man is essentially the arcade game loop with an additional sub-loop (Eat Dots -> Eat Fruit, Repeat). You’ll also notice that there is no way to get from the Eat Fruit bubble to the Next Level bubble. This is because in the game Pac-Man eating fruit is not required to progress, but eating dots is, and so our diagram reflects this. In fact, you could probably remove the Eat Fruit completely and still have the essence of Pac-Man. This tells us that although Eating Fruit increases your score and feels good to do (it provides an added challenge) it isn’t a core game mechanic and could be removed without drastically changing the game (it does change the game feel, but more on that in another post).

Your core game loop may also have sub-loops. Going back to our generic RPG game loop you could argue that not every fight gives you enough of a reward to level up. Most RPGs include some sort of grinding where players must have several enemy encounters before they level up. Similarly, some adventure games may follow the generic Puzzle diagram, but may require the player to solve multiple puzzles before moving to the next area. More complicated diagrams that takes this into account might look like the following:

Unlike the digram for Pac-Man where Eating Fruit was optional, none of the bubbles in these diagrams can be removed without breaking the loop indicating that each bubble is an important part of the game.

Try diagramming the core gameplay of your game. While making your core game loop diagram make sure that each part of your game loop supports the essence statement you wrote above. If you run into a problem and don’t know the best way to represent a part of your game just take your best guess (you can always update the diagram later).

Done? Beautiful!

Now do it again. No, really. This time try and see if you can reduce the number of bubbles without changing the core of your game. If you can’t, great, you’re done.

Noun/Verb Diagram

Another way to diagram your game is to use the Noun/Verb diagram technique. This technique tries to visualize what a player can do by showing the relation ships between the important objects in your game (nouns) and the actions a player can take (verbs). This exercise is particularly helpful if you don’t what the major mechanics in your game are. In this section we’ll create a Noun/Verb diagram for the game Pac-Man before creating one for your own game.

First, we need to identify all the major objects in our game. For Pac-Man this includes the Player, the Ghosts, the Dots, the Fruit, and some none obvious things like the score. Because this diagram is focused on player interaction these nouns generally do not include things that only exist in your code such as a game state controller, UI controller, etc. Next, draw lines between any two nouns and use a word or two to describe how they interact (verbs). For example Ghosts -Chase-> Player and Player -Eats-> Dots. The result should look something like this:

You’ll notice that in this diagram the player has the most arrows pointing to/away from it. This makes sense since you generally want your game to revolve around the player and their actions. If you find that some other object has more actions associated with it, consider why that might be the case and see if you can’t shift the focus back to the player.

Take some time to create a Noun/Verb diagram of your game. Make sure that the diagram you create matches with your essence statement and edit accordingly.

Editing / Focus on the core mechanics

If you finished the exercises above you might notice that some elements of your game didn’t make the cut. That’s ok, in fact, editing your game to focus on the core mechanics is a good thing. If you found the previous exercises difficult, or struggled to fit all your mechanics into 1-2 sentences, it might be time to rethink what mechanics are core to your game. In order to address this, think go back to your essence statement and think about the core experience you want to present to your players. Ask yourself if all of the mechanics you’ve identified above reenforce, or distract, from that experience and cut the ones that don’t fit.

It’s generally better to get one core mechanic right than to have several that aren’t very fleshed out. If you’ve ever played a game where it feels like a certain part was added as an after thought, you know what I mean. Another way to think about this is, unless the game was focused on crafting, a crafting system would be really out of place in a Mario game. In fact, having a crafting system might really detract from the platforming mechanics that are at the core of most Mario games. So don’t be afraid to cut out the unnecessary elements. This part is difficult, and it’s a good idea to keep a notebook handy to write down any of the ideas you like, but don’t exactly fit into this game. Who knows, maybe they’ll be the core of another game.

Editing is hard, and if you’re having a difficult time with it just know you’re not alone. The great youtube series Extra Credits has an excellent video on editing that I highly recommend watching if you’re having problems with this part of the design process.

If you feel that your game is a bit lean now find ways to iterate on your core mechanic rather than introducing new mechanics to flesh out your game. Nintendo does a great job of keeping their games focused to a few core mechanics which they then use multiple times in new and interesting ways.

A big part of translating Mario from 2d to 3d in Mario 64 was making sure that Mario jumped around in fun and interesting ways simply because jumping was the core mechanic. As Miyamoto stated in an interview for the Mario 64 strategy guide,

For your game this might mean revisiting a mechanic that you haven’t fully explored and seeing new it can be used.

Conclusion

By now you probably have a much greater understanding of your game’s core game loop and the core mechanics that support it. These diagrams will serve you well during development whether you use them to communicate ideas with your development team, or fight against feature creep by using these diagrams to edit. If you come up with any cool Noun/Verb diagrams or interesting game loops contact us, connect with us on Facebook, or let us know on Twitter. We’d love to hear more.

Till next time, game on!

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