Game systems: An in-depth look at gacha boxes

As more and more games transition to, or are created in, the free-to-play model, certain free-to-play mechanics have come under greater scrutiny.

One of the more contentious forms of free-to-play game design is loot boxes and gacha boxes. Like them or not, these mechanics form one of the most consistently profitable underpinnings of the free-to-play game model.

A lot of the press on loot and gacha boxes is focused on their exploitative nature and their potential links to gambling and so-called gaming addiction.

In this article, we’ll be taking a less sensationalized look at these particular mechanics and their impact on the gaming industry.

What is a gacha box?

The term gacha actually derives from the Japanese word Gashapon. Gashapon is a type of vending machine from Japan that dispenses toys.

What made these machines unique was the toys had varying levels of rarity and the more money you put into the machine, the greater the chance of you getting a rarer toy.

This mechanic quickly made its way into Japanese mobile game design and has been part of their free-to-play economy since around 2011.

The system made its way over to the Western free-to-play market, where its unparalleled ability to part players from their disposable income quickly saw it incorporated into around 58% of the games in U.S. top 100 grossing iOS games.

Are a gacha box and a loot box the same thing?

While both loot boxes and gacha boxes are similar free-to-play mechanics, they aren’t exactly the same.

Both limit the possible reward for buying them by using random number generation (RNG) and both provide the chance to win in-game items in exchange for real-world money.

The primary difference between a gacha box and a loot box is that loot boxes have a static output rate and cost.

For example, if a look box costs $10 and has a 10% chance of dropping a certain item, then all other loot boxes will cost $10 and have the same 10% chance.

Gacha boxes have a scaling factor of money spent to percentage drop potential.

If the lowest level gacha box costs $5 and has a 5% drop chance for a certain high-level item, then the $10 box would have a 10% chance, and the $15 box would have a 15% chance, etc etc.

Why all the controversy?

Much of the controversy surrounding loot boxes and gacha boxes don’t actually come from the free-to-play gaming industry. Instead, much of it is generated by the inclusion of free-to-play mechanics into full-priced AAA games.

Look boxes, in particular, have become a hugely controversial inclusion in a number of multiplayer first-person shooters, with Start Wars Battlefront 2 becoming the poster child for games where monetization was more important than player experience.

Understandably, players who had already paid $60 and up did not appreciate content they had already paid for being walled off behind an RNG-based mechanic that cost yet more money.

This is in contrast to the free-to-play model where there is no upfront spend to access the games.

Because of the increased visibility of these mechanics and the controversy that surrounded them, loot boxes and gacha boxes have been linked with both gambling and the concept of gaming addiction.

Are gacha boxes gambling?

To date, the only form of gacha box that has been declared illegal is the kompu gacha or compu gacha, also known as the complete gacha.

Under this particular system, players need to collect a set of basic items in order to create a rarer item. While it was easy to gain the first few times, it became increasingly unlikely that each new gacha box bought would complete the set.

This is sometimes referred to as the Coupon Collector’s Problem.

Japan’s Consumer Affairs Agency declared that complete gacha was a form of gambling, and therefore illegal, citing the Law for Preventing Unjustifiable Extras or Unexpected Benefit and Misleading Representation.

There are, however, still 10 to 15 gacha varieties still in regular, completely legal use in games around the world.

Do gacha boxes cause ‘gaming addiction’?

There is no question that some people have a problematic relationship with gaming. However, the concept of gaming addiction as a widespread problem or potential mental illness is still one that requires further scientific research.

One of the more popular statistics for gaming addiction, taken from a study by Koepp et al. published in Nature in 1998, indicates that video gaming increased the amount of dopamine in the brain by about 100%.

Since dopamine is linked to the little-understood reward system of our brain, this is taken to indicate that video games have the potential to be addictive.

However, when put into context, the study is a little less alarming. Exercise, sex, and meditation have also been found to increase the dopamine levels in the brain by similar amounts, while methamphetamine, a genuinely addictive substance, increased the dopamine levels in the brain by 1000%.

Additionally, as pointed out by Markey and Ferguson in 2017, around two billion people worldwide enjoy video games every day. If video games were even slightly as addictive as other illicit substances that cause dopamine levels to spike, the scale of the epidemic on our hands would be unprecedented.

The reality is that ‘gaming addiction’ is a badly understood, under-developed, and under-researched subject, making it very hard to point to a particular mechanic and say with any certainty that it causes any kind of addiction.

Are gacha boxes a good design?

The relative strengths of gacha as a free-to-play mechanic are somewhat dependent on who the person making the judgment is and how well the gacha mechanic has been implemented.

From a game developer’s perspective, gacha has proven to be a consistently profitable free-to-play mechanic. This has allowed free-to-play game designers to create and bring to market games that otherwise might not have existed.

The reality is that more than 85% of the games industry’s total revenue comes from free-to-play games. That revenue is vital to the existence of many of the most successful game developers and some of the most popular games on the market.

From a player’s perspective, whether or not gacha is a good design depends entirely on how well it has been implemented.

It’s hard to dispute that implementing gacha and loot box mechanics, with their ‘pay to win’ association, into already online multiplayer FPS games was probably a bad idea.

That level of monetization, poorly implemented, can hugely unbalance a game and irreparable harm both the player experience and the game developer’s and distributor’s reputation.

However, there are numerous examples of games that have implemented gacha in a way that provides consistent revenue for the developer without harming the player experience.

Some good examples include Fire Emblem Heroes, Another Eden, Genshin Impact, Star Wars: Galaxy of Heroes, and Final Fantasy: Brave Exvius.

These games work because the gacha system has been properly implemented.

How to design and implement effective gacha

Designing your own gacha system can be boiled down to three key factors: depth, width, and desire.


The depth of your gacha will determine how long your gacha mechanic remains attractive to the player. The primary factors that make gachas unattractive to the player are:

  • A lack of content, removing the player’s need to pull from the gacha boxes.
  • A lack of meaningful progress or reward, which can frustrate the player.

In order to maintain the correct depth for your gacha, you need to model its course using a tool that offers a way of keeping in check the dynamics that emerge from the rules you set as part of this mechanic, as with any mechanic
you introduce. This is where Machinations excels. First of all, as opposed to other tools, Machinations diagrams are not static. This is important as games are highly dynamic systems. This allows you to visualize all the interconnected mechanics of your game, and spot the dynamics they generate.

Here’s an example of how a gacha looks like in the context of the core loop. The model is a deconstruction of Dungeon Fighter Online, and it simulates item and material acquisition, experience gain, item drops, and stamina management.

Hit play and visualize how the systems work together:

  • The player enters dungeons in order to gain XP, farm materials, gold, and equipment
  • Each dungeon has 6 rooms and a boss fight at the end
  • When finishing the dungeon Clearance XP and Hunting XP are awarded
  • Items come in 7 different rarities. The common ones should always be sold for the best value
  • The player has 156 fatigue points that reset at the start of each day. Every room that the player enters while in a dungeon will cost 1 FP. When the player runs out of FP, he will be unable to enter dungeons that day

When designing your gacha, you’ll want to create a model that slows the speed of progress relative to time in-game and percentage completion of whatever the gacha is dropping. Machinations allows users to define rules of how a player may interact with the game, and then simulate these interactions over time. In this way, you can experiment and gather quantitative data from thousands of simulated play sessions quickly and efficiently. To support this, Machinations features automatic charts and data analysis from each simulated play session. Add the diagram above to your Machinations account, and perform QuickPlays, to simulate several days’ worth of gameplay.
When designing your own gacha model, you should take into account variables such as:

  • The amount of content you have available
  • What use your game has for duplicates
  • Your amount of rarities, and their drop rates
  • How your gacha pool changes

In order to increase your gacha’s depth, you can always add more content, add new uses for duplicates, change to drop rates, or change the pool the gacha draws from.


The width of your gacha reflects how the system encourages players to acquire as many of the gacha drops as possible and how it offsets bad drops.

Introducing different game modes, rewards for having larger teams, larger loadout sizes, and implementing explicit strengths and weaknesses can all encourage players to want more gacha content.


Need represents how much your players require the gacha in order to progress in your game. The level of need is specific to each individual game and is probably the most difficult thing to balance.

If players need to rely wholly on the gacha to progress, then you risk frustration and player churn. If they don’t need the gacha at all, then you’re losing money. Mapping your whole game in Machinations will help you in this balancing task. As you’ll be able to understand the gacha your deigning in the context of all other mechanics and simulate your players’ progression interrelatedly. Moreover, you can tweak parameter sets to simulate different types of play styles, to make sure your systems work for each type of player and skill level.

The trick is to find a level where the players feel like using the gacha is a tactic they use as part of their skillset. Something that compliments their playstyle, rather than replaces it.

How to properly implement gacha

As a rule, there are two different approaches to gacha implementation: rarity and utility.


The first gacha is based on the rarity of the drop.

The player starts with a very common set of items, cards, heroes, or whatever content is being used. They then use the gacha system to pull new content with the percentage chance of each drop being linked to its rarity.

The ‘need’ part of this design is that the rarer drops are far more powerful than those that are more common.

There are several problems with this kind of gacha implementation

Firstly, it raises the ever-present specter of ‘pay to win,’ How effective you are in-game inextricably linked to how much you spend on the gacha and whales (players who spend a lot of money) can simply buy their way to the top of the games.

Secondly, because they are the most valuable, the player only cares about the rarest characters, and an inability to access them, possibly because of poor RNG, can block their progression in the game and cause them to stop playing.

This means the designer has to constantly find a way to try and make everything but the rarest content relevant to the player.


The second and arguably better implementation of gacha allows the player to rank up content by finding duplicates of it.

This allows the player to use the items, cards, or team that appeals to them, even the ones they start with, while still encouraging them to use the gacha to improve them.

Rather than entirely focusing on end game content, in this case, the rarest drops, this version of the gacha system encourages the player to consistently collect and upgrade a wide variety of content because it allows them to develop their play style.

This approach significantly increases the utility of all the gacha drops.

Those with a specific playstyle can continue to progress without abandoning it or having it invalidated by super-powerful, but very rare, items, cards, or characters.

A good example of this system being well implemented is Marvel Strike Force.

A reputation and implementation issue

At the core of the issues around gacha boxes is their poor reputation among certain gamers and their poor implementation.

Gacha boxes and loot boxes are inextricably linked to issues around gaming addiction and gambling in games.

At the same time, badly implemented gacha and loot box mechanics, especially in AAA games, have left a sour taste in the mouth of gamers.

However, when implemented properly, gacha can provide the revenue that many game developers rely on, without massively compromising the quality of games they are creating.