How to Design a Game’s Core Loop

Turn the Premise into What the Player Actually Does

“Manage a paper city,” “explore ruins,” and “protect a village” describe premises, not core loops. A core loop must identify the decisions and actions the player can make repeatedly. Start by completing this table:

A loop can consist of one operation or span several steps. What matters is that action and outcome connect back into one another, not that the design contains many verbs.

Use One Causal Sentence to Check Whether the Loop Closes

Write every core action in this form:

Current state + player action + world rule → new state + feedback the player can read + new opportunity

For example: “The wind gate faces north, the East District’s flags hang limp, and its filter is clear + the player turns the tower's wind gate toward the East District + wind can reach only one district at a time → the East District's paper wheel begins turning + rooftop flags rise and streetlights come on + the player can enter the East District and inspect the next blockage.”

“Click the wind gate; energy increases by one” gives neither the state meaning nor the opportunity that follows. “Play an East District story scene” likewise fails to explain why the world responds to this action. A number can still appear, but it must correspond to a change in the situation that the player can perceive.

Original Design Example: The Night-Shift Wind Gate of Paper City

The following is a paper design, not a report of a build or playtest. In this fictional game, the player is Paper City's night-shift maintenance worker. The city has only one stream of mechanical wind, which can be sent to only one district at a time. Each district has a paper wheel. Once its wheel turns, it powers the local elevator and lets the maintenance worker reach higher areas. Dust clogs the filter in whichever district currently receives wind. The degree of blockage is shown through the height of its paper flags, the sound of its gears, and a gauge beside the wind gate.

Goal of one cycle: Restart one stalled paper wheel and reach that district's upper platform.

Representative path: The player first sees the East District's flags hanging low with its filter clear, while the North District's filter is close to clogging. They keep the wind in the North District for the moment, clean its filter, and then redirect the wind east. The East District's paper wheel turns and its elevator opens. The North District loses wind, but its filter has regained capacity. On reaching the East District's upper platform, the player learns that the wind must be redirected again before the West District's freight elevator can start in the next cycle.

A low flag can mean no wind or blockage, so it alone does not identify the cause. Read wind direction, the gauge and actual filter condition too. Cleaning restores the stated capacity without promising an unspecified duration.

Along this path, cleaning prevents the old blockage from carrying into the North District’s next wind supply, turning the wind gate changes spatial opportunities, and reaching the upper platform establishes the cycle's final state. If cleaning the filter merely plays an animation and never affects the wind-delivery result, it does not belong in the core loop.

Walk One Representative Path and Record Each Before-and-After State

Do not stop at an arrow diagram. Choose a normal situation and move from the defined initial state to the end marker:

1. Record what the player sees first and what decision that information supports.
2. Record the specific action the player takes and its prerequisites.
3. Record how the rules process that action, including conditions for rejection or partial success.
4. Record which facts the outcome changes and which remain unchanged.
5. Record where the player reads the change and what new opportunity it creates.
6. Repeat until the segment ends, then list the final state.

If the designer has to explain a step aloud, the rule or feedback still has a gap. If the player takes the same action every cycle without reading a new state, the loop may be repetitive labor rather than a meaningful decision. Add a world response that truly changes the next judgment, or narrow the gameplay promise.

Use a Deletion Test to Find False Core Systems

For each system, imagine deleting or automating it, then ask:

• Does the player still make the same core decision?
• Does the world still reach roughly the same result?
• Do the later opportunities change?
• Does the distinctive pressure promised by the source or concept still exist?

In the Paper City example, automatically selecting the district that lacks wind would leave the player with little more than walking to the gate and pressing a button; the allocation decision disappears. Automatically cleaning the filters would remove the tradeoff between redirecting the wind now and preserving capacity first. By contrast, adding a collectible badge to every upper platform is supplementary content if the badges change no route, rule, or result. The first loop can omit them.

The deletion test controls the scope of the core. It cannot prove that the remaining loop is fun. Feel, comprehension, and pacing still need to be observed after a build exists.

Common Failures and Fixes

FAQ

Does a core loop always need to consume a resource?

No. Spatial change, information gained, character responses, mastery of an action, or newly available opportunities can all close a loop. Include a resource in the core only when it genuinely changes which actions are available and what consequences they have.

Do story games need core loops too?

Yes. Define how the player repeatedly interprets a situation, takes action, and sees the world respond. The loop may involve investigation, negotiation, or choice, but it cannot consist only of turning pages without any player-driven state change.

Related reading

• Adapt a novel into a game: pick a playable slice, then build→
• Adapt a novel scene into meaningful choices and endings→
• Novel to Game→