How to Design Gacha Systems
Deep dive into mechanics that drive player spending
These are my key takeaways after reading Gacha Game Analysis and Design and What aspect of Genshin Impact makes players spend money?
1. For Single Item Gacha games, align the cost of winning (pulls × price per pull) with the optimal reserve price in a Myerson auction. Focus on whale property for revenue maximization.
Researchers explore strategies through the lens of game theory and something called the whale property—a scenario where the most logical strategy is to either go all in or not play at all. While this approach may seem extreme, it only makes sense when the rare reward is something the player truly WANTS.
When spenders of Genshin were interviewed they revealed that they spend because of their emotional attachment to specific characters or items, like Wanderer because he was present in the game’s lore for a while before he became playable. In this time, players got to know him, understand his backstory that built anticipation for his eventual release.
While not directly related to a single item, the constellation mechanic in Genshin also reinforces the whale property by incentivizing players to continue pulling for duplicate characters even after acquiring them to “max out” their stats. They value these rewards so highly that they rationalize spending large amounts, so systems designed with the whale property in mind maximize revenue.
Mathematically, single item gacha systems are very similar to auctions, specifically the Single-Bidder Myerson Auction—an auction mechanism where the seller is unaware of the buyer's true valuation but aims to maximize revenue. In this context
Each pull functions like the player placing an indirect bid, driven by how much they value the item.
If the item or character is highly desirable, the player is willing to spend more on additional pulls to increase their chances of winning.
By modeling player valuation distributions (using market research, player data, A/B Testing..etc), developers can calculate an optimal reserve price, making pricing less arbitrary and more aligned with whale behavior.
2. For Multi-Item Sequential Gacha prefer the succeed-after-winning mechanism to build on player progress and maximize revenue instead of reset-after-winning systems.
When we move beyond single item gacha games, researchers focus on two types of gacha mechanics which affect player strategy and behavior - Sequential Gacha and Banner Based Gacha
Sequential gacha: Players progress through stages and phases, like conquering a level to unlock the next. You can eventually unlock all the pieces. But what happens once you get what you’ve wanted? Two reset systems come into play: reset-after-winning and succeed-after-winning.
Reset-After-Winning: Players start fresh every time they complete a certain stage, constantly chasing the next reward. For example, in Genshin Impact, it always feels like you’re starting over.
Succeed-After-Winning: Here, the player progresses to the next item after winning the current item. Counterintuitively, this approach has a mathematical edge over the reset-after-winning method in terms of maximum revenue generation due to varying costs, even though it benefits players.
Pity System Influence: Progress toward the pity threshold, carries over to the next item. Players nearing the pity threshold for the first item are incentivized to keep pulling because they'll likely get the second item at a reduced cost. Genshin players also frequently reference the "pity system," which guarantees a 5-star item after a certain number of pulls. So players frequently plan their spending around this system, lowering the expected cost of subsequent wins.
Reduces Expected Cost: The carryover creates a dynamic pricing structure where later items have a lower expected cost. This makes them more attractive and encourages continued spending even after obtaining the first item. Even after reaching the pity threshold in Genshin, the 50/50 mechanic (where there’s only a 50% chance of obtaining the desired character) extends engagement by incentivizing additional pulls. Every pull feels like progress. Players—even those hesitant at first—keep pulling because they want to see their efforts pay off. It also taps into the desire to complete sets, making each win feel more rewarding than it actually is.
Strategic Play: Players can strategically spend to get the most valuable items at the lowest cost. This strategic element, combined with the lower expected cost of later items, can lead to more spending than in reset-after-winning, where the cost for each item is constant.
3. For Banner-Based Gachas, implement the succeed-after-opt-out mechanism to increase retention of budget-constrained players.
Banner-based gacha systems, being limited-time events, introduce a strategic layer for players who must decide whether to pull for the current banner or conserve resources for future ones. “Do I pull now, or do I save my resources? Is this event worth participating in?”
Interviews with a small sample group of non-spending Genshin Impact players revealed regret about skipping banners featuring 5-star characters they wanted, citing budget limitations or prioritizing other banners.
Resetting progress after skipping a banner can frustrate players, leading to churn and reduced long-term engagement.
The delayed gratification for Welkin Moon - 300 Genesis Crystals + 2700 Primogems over 30 days vs immediate gratification (Genesis Crystals - only 300GC) hints at an interesting optimization problem.
It can be inferred that the succeed-after-opt-out mechanism aligns with this preference by allowing for gradual progress towards desired items. Players can make incremental investments over time, accumulating pity or other bonuses, rather than being forced into a large, potentially intimidating, upfront transaction so they cater to budget-constrained players.
4. For banner-based gachas, either keep future banners secret OR strategically sequence them by leading with less desirable banners, followed by highly desirable ones.
Grinding to earn free gacha pulls, serves as a subsidy to encourage player engagement and potentially incentivize spending
In fixed-probability gacha systems, where the odds of winning remain constant, subsidies reduce revenue because they don’t encourage additional purchases. Players simply use the free pulls without needing to spend more.
Subsidies are more effective in varying-probability gacha systems, where the odds of winning increase with each pull. For players with low valuations who are hesitant to spend, these subsidies can nudge them toward making additional purchases to secure a win.
However, in banner-based gachas, subsidies can lead to grinding and resource hoarding. Players may save up free pulls, delaying spending for high-demand events, which hurts the developer in the short term. To counter this, developers can:
Keep Future Banners Secret: This creates uncertainty, encouraging players to spend resources now rather than hoarding.This strategy, however, has a trade-off. While it might encourage immediate spending, it can also lead to player frustration, especially if they perceive a lack of transparency or feel pressured to spend without sufficient information.
Sequence Banners Strategically: By combining strategic banner sequencing with a calculated distribution of free gacha pulls, developers can manipulate player behavior to some extent. For instance, providing a generous amount of free pulls during less desirable banners could incentivize players to use them, depleting their resources. Then, during a highly anticipated banner, the reduced availability of free pulls could push players towards spending money.