How Offline Earnings Work in Idle Games (A Developer Explains)

Why you only get part of your income while away, why there is a cap and how to collect more. The real formulas from three idle games we made, next to Cookie Clicker and Egg, Inc.

Offline earnings are the coins, gold or cookies an idle game hands you when you come back. The game does not keep running on your phone while it is closed. When you leave, it saves the time. When you return, it measures how long you were gone, cuts that to a limit and pays you a share of your normal income for it.

We make idle games for Android, so we can show you the actual code that does this. Below are the rules from three of our games, Idle Ronin, Idle Summoner and Idle AI Factory, next to two classics, Cookie Clicker and Egg, Inc. Every idle game uses some version of the same formula, and once you know it, you can plan your breaks around it.

Does an idle game keep running when it is closed?

No. Android pauses apps in the background and closes them when it needs the memory, and a game that really ran all night would drain your battery. Idle games fake it instead. The moment you leave, the game writes the current time into its save. When you open it again, it subtracts that time from the current time, and that difference is your time away.

Everything else is arithmetic done in the first second after loading. That is why the "Welcome back" popup appears so quickly even after a whole day, and why the result does not depend on whether your phone was on, off or in airplane mode while you were gone.

It also explains one old trick: moving the phone's clock forward. A game that trusts the device clock can be fooled into paying for time that never passed. Many games now check the time against a server or refuse to pay when the clock jumps backwards, and a clock change can also mess up daily rewards and timers, so it is rarely worth it.

The offline earnings formula

Stripped down, almost every idle game pays you this:

offline earnings = min(time away, cap) x income per second x efficiency x bonuses

• Time away is measured when you come back. Most games ignore very short breaks, so switching apps or watching a video ad does not count as a trip away.
• The cap is the longest break the game will pay for. Anything past it is lost.
• Income per second is what you earn while playing, often with temporary boosts removed.
• Efficiency is the share of that income you get while away, from a few percent to 100%.
• Bonuses are upgrades, gear, pets or purchases that raise the cap or the efficiency, and the popular "watch a video for double" button.

Here is how the numbers look in real games:

The numbers for our games come straight from the game code. Cookie Clicker's rules are documented on the Cookie Clicker wiki, and Egg, Inc.'s silo rules on the Egg, Inc. wiki.

The chart turns those rules into something comparable: how many hours of normal income you have collected after a break. Idle Ronin pays close to full value for 8 hours and nothing after that. A fresh Idle AI Factory save pays 10% for 2 hours, so a whole night away is worth about 12 minutes of play, until you research better offline rules. Idle Summoner's invasion income pays only 20%, but for a full day, so it rewards a once-a-day player.

Why is there a cap on offline earnings?

Players ask this more than anything else about idle games, and the honest answer has four parts.

It sets the rhythm of the game. A cap tells you how often the game expects to see you. Eight hours matches a night's sleep or a work day. Twenty-four hours means once a day is enough. Two hours is a nudge to look in during the day, which is why we raise it through upgrades rather than start with it high.

It keeps playing worth more than not playing. If a week away paid a week of full income, opening the game would be pointless. Caps and efficiency together make an active session count.

It protects the economy. Idle games grow exponentially. An uncapped payout after a long break can skip hours of content in one tap and break the balance of everything that comes after it.

It is also a product. Many free games sell a longer cap or a higher efficiency. We do it too: the Cyber Card in Idle Ronin adds 4 hours to the cap, and the Mega Bundle in Idle AI Factory doubles offline earnings. You should know that when you decide whether a purchase is worth it.

Why do you earn less offline than while playing?

While you play, you tap, fire skills, catch bonuses and use boosters. None of that happens while you are away, so the base rate has to be lower, or tapping would be a waste of time. The efficiency percentage is the dial designers turn.

It also lets a game offer a long cap without breaking. Idle Summoner can pay for a full day because it pays 20% of the invasion income for it. Idle AI Factory starts low, at 10% for 2 hours, and hands you the rest as upgrades: each level of Night Shift research adds an hour to the cap (six levels), each level of Dream Engine adds 5% efficiency (six levels), and two collectible robots, Chronos and Luna, add a bit more.

There is one more detail most players never notice. Idle AI Factory does not use the income of the last second you played, because a booster or a burst of truck taps could have tripled it. It keeps the rate between a slow and a fast delivery trip, so a booster that happened to be running when you closed the game does not count for eight hours.

Two ways to calculate it: a rate or a replay

Most tycoon games multiply a rate. That works because their income is steady: floors produce, trucks deliver, managers keep businesses running. Idle AI Factory and Idle Summoner both work this way.

Idle RPGs have a problem with that. Your income depends on which enemies you are fighting, and progress stops at a boss you cannot beat. So Idle Ronin replays the fight instead. It works out how much damage your squad would have dealt in the time away, including its critical hits, then spends that damage on enemies one by one. Every defeated enemy pays about the same gold as in normal play (a share of its health). Each boss is checked against your boss timer. If your squad could not have beaten it in time, the replay stops advancing and farms the last wave before that boss for the rest of the break.

That is why you can open Idle Ronin in the morning and find that you cleared ten stages and picked up Unit Cores overnight, and also why progress sometimes stops at the same boss where you left it. Skill cooldowns tick down during the break too, so your skills are ready when you return.

Why did I get no offline earnings?

When the popup does not show up or pays almost nothing, it is usually one of these:

• The break was too short. Idle Ronin and Idle AI Factory ignore anything under 3 minutes. Idle Summoner starts counting invasion income after 5 minutes and shows its gold bonus after an hour.
• You passed the cap long ago. Two days away pays the same as the cap, not more.
• Your income rate is zero. A factory with no working floors or a squad with no units has nothing to multiply.
• The clock changed. Time zone jumps, a manual clock change or a phone restored from a backup can make the time away look negative or huge, and games clamp it to be safe.
• The save was replaced. Loading a cloud save on a new phone brings back your progress, not the offline time on the old phone.

How to collect more offline earnings

1. Check in at the cap, not later. With an 8-hour cap, opening the game before bed and after waking up loses almost nothing. With a 24-hour cap, once a day is enough.
2. Spend before you leave. The payout uses your income rate when you come back, which is the one you left with. Buy the upgrades you can afford before closing the game.
3. Buy offline upgrades early when the efficiency is low. In a game that starts at 10% for 2 hours, a few levels of cap and efficiency upgrades are worth more than almost anything else for a player who checks in twice a day.
4. Save the video multiplier for full breaks. A x2 or x5 button is worth the most after a long break, when the payout is at its biggest.
5. In idle RPGs, leave with a squad that can win. A replay stops at the first boss your squad cannot beat. If you are stuck, upgrade or rebirth before a long break, so the night is spent on new stages instead of farming old ones.
6. Leave the clock alone. The gain is small, and a clock change can break daily rewards, timers and leaderboard results.

FAQ

Do idle games earn money when your phone is off?

In effect, yes. The game calculates what you earned when you open it again, so it does not matter whether the phone was on or off. What matters is the time that passed and the cap.

Do idle games need the internet for offline earnings?

Usually not. The calculation uses the phone's clock and your save, which is why idle games are popular for flights. Some online games check a server clock first. The core game in all four of our games runs without a connection; ads, purchases, cloud save and rankings need one.

Is it better to leave an idle game open?

Playing earns more than being away in almost every idle game, because offline efficiency is below 100% and active bonuses stop. But leaving the screen on just to earn drains your battery. If a game pays well offline, closing it and returning at the cap is the calmer way to play.

Why is my offline income lower than my income per second suggests?

Because of the efficiency percentage. A game that shows 1,000 coins per second and pays 10% offline gives you 100 coins for each second you were away, up to the cap. Temporary boosts are usually left out too.

Offline earnings are one of the pillars of the genre. For the rest of it, read our complete guide to how idle games work, and for a game built around generous offline rules, try Idle Ronin.

Sources

• ONI Games game code, September 2026: Idle Ronin (LiveOps.cs, Engine.cs), Idle AI Factory (Balance.cs, Economy.cs, SaveManager.cs) and Idle Summoner (game_manager_script.cs, invasion_script.cs).
• Offline Cookie Production, Cookie Clicker wiki.
• Grain Silos, Egg, Inc. wiki.
• Anthony Pecorella, The Math of Idle Games, Part I, Kongregate / Game Developer, 2016.