A mechanic that accumulates in-game currency over time, but requires a small purchase to unlock and collect what has built up.
Best for
Achiever
Context
Monetization
Motivation drivers
OwnershipAvoidanceScarcity
How it works
Earned value awaiting release
The piggy bank converts time played into a purchase prompt that feels earned rather than demanded. The user watches their bank fill through normal gameplay. When full, they are prompted to unlock it, typically for a small payment. The key psychological shift: the user is not buying currency, they are unlocking currency they have already earned.
Core principle
Earned value awaiting release. The purchase feels like a harvest, not a transaction.
Watch out for
Piggy banks must fill at a rate that feels meaningful. Too slowly and users forget it exists. Too quickly and the unlock price feels arbitrary.
Structural variants
Three ways to build it
01
Currency bank
02
Resource accumulator
03
Reward chest accumulator
Lifecycle placement
Mid-to-late lifecycle. Most effective once the user cares about the currency being accumulated.
Case studies · 1
Seen in the wild
Solitaire Grand HarvestCasual Game
screenshot
Peggy visible in the top-right corner, fat and maxed out, with the balance showing 35,000 credits and the "Peggy just got maxed out" message
screenshot
The Peggy introduction screen with "Win or lose any solitaire level, Peggy will add bonus credits to your savings. Collect your savings for a great price" and the $3.99 price
How they use it
Peggy is introduced at level 18 with a seeding deposit of 4,050 credits already loaded, giving the bank immediate visible value before the player has done anything to earn it. It fills automatically with every level played, win or lose, capping at 35,000 credits. At the cap, $3.99 unlocks the accumulated amount. Once capped, Peggy becomes a persistent non-dismissible presence with a two-day countdown timer.
Why it works
The seeded starting deposit accelerates the endowment effect, the bank already feels partially yours before a single level is played. By the time it caps at 35,000 credits, the $3.99 unlock feels like reclaiming what play has already earned rather than a store purchase. The non-dismissible presence at cap creates persistent visual pressure without additional prompting.
The detail
Peggy surfaces as a persistent screen element after reaching her cap. The cap indicator is visible throughout the session. When Peggy takes the position held by 30-minute rotating purchase offers, she appears most prominently after each level completion.
Takeaway
The bank is seeded with 4,050 credits at introduction ('your first credit deposit is on us'), ensuring the balance is non-zero and visibly growing from the first moment.
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