Introducing Chainbinders: A Next Generation NFT Gacha Experience [EN]

Doki Doki
9 min readApr 8, 2021


Update 4/10: Chainbinders LGE is now live at:

Hi everyone! Roy here. As I write this, we’re just a few short days away from the official launch of Chainbinders, Doki’s most revolutionary gacha experience yet. The project has been a silent build up over the last few weeks, and details regarding how it all works have been pretty under-wraps ever since. Given that we’re so close (as of the publishing of this post) I thought I’d take the time to go over all of the fine details regarding Chainbinders.


The world of Chainbinders takes place in the near future — a large solar flare brings humanity to the brink of extinction, the ensuing chaos bringing about the destabilization of society. The solar flare kills most of the humans it comes in direct contact with — but a few destined children around the world survive the event, gaining mysterious powers. The focus of the story revolves around fifteen of these children, who come to be known as Chainbinders — named such for their unique and singular appearance. Chainbinders seek their Collectors, individuals with the ability to restore a Chainbinders to their full strength.

The Chainbinders Gacha machine will feature over 100 cards from the Chainbinders universe, including 15 Legendary rarity Chainbinders. In addition, there are innovative crypto mechanics designed in such a way where the NFTs have on-demand liquidity, and are certain to become increasingly scarce and valuable over-time. As part of our mechanics, $DOKI and $AZUKI are cleverly integrated into the system, so be sure to read until the end to find out how they will be used! To be able to deliver on all of the mechanics and game theory we planned, Chainbinders will use 1) an original token, known as BND, and 2) A custom coded Gacha contract. Let’s go over the mechanics now.


BND will be the only way to play the Chainbinders Gacha machine and obtain the NFTs. In order to get BND, there will be a one-time sale a.k.a LGE (Liquidity Generation Event) for 21 days where everyone will have the opportunity to purchase BND with ETH. After the LGE, BND will be unmintable, and the only way to get BND will be to purchase it from someone else on the open market. BND spent to play the Gacha machine will be burned forever, making BND a hyper-deflationary token. We expect the circulating supply of BND to quickly approach zero following the activation of the Gacha machine.

100% of BND minted will be done through the public LGE. There is no presale, seed round, or other team incentives in BND. This is to ensure a completely fair distribution, and to fully realize the other Chainbinders mechanics.

In a few days, the Chainbinders LGE will be activated on the official website:

The Reserve Pool

75% of the total ETH used to purchase BND will be sent to what’s called the Reserve Pool. This pool is a custom audited smart contract that backs the value of every NFT in the Chainbinders Gacha machine.

Chainbinders NFTs will be instantly redeemable for a percentage of the total ETH in the reserve pool. Redeeming a Chainbinders NFT is what is called in-lore as Unbinding.

It is possible that a user mints a nominal amount of BND, rolls on the Gacha, and wins 100x or more of his buy-in in redeemable value.

Naturally, the Reserve Pool lowers in absolute ETH terms over time as users Unbind their NFTs. However, the act of unbinding a Chainbinders NFT also triggers some interesting crypto mechanics which rewards long-term collectors. The next section explains this in detail.


Unbinding is what makes Chainbinders a first-of-its-kind deflationary NFT collection with measurable appreciation in real value over time.

A user who Unbinds an NFT will relinquish all future rights to the Reserve Pool for that NFT (as it is burned) and their previous percentage ownership is now split up among the remaining Collectors. Additionally, they pay a 15% Unbinding cost with 10% going back to the Reserve Pool, which further bolsters the Reserve Pool and long term value proposition. The other 5% will be used for $DOKI buybacks. The user then receives 85% of the redeemable value in Ethereum, thus granting instant exit liquidity to any Chainbinders NFT.

Hey Doki Squad! It’s Rei. I will explain the math behind the mechanics. Let’s dive in!

For simplicity’s sake, let’s assume just 1 rarity tier, which means that each NFT is worth an equal % of the reserve pool:

Let R = Initial reserve Pool

Let N = total number of NFTs in the set

Let Xn = nth NFT unbound, n = {1,2,3,…,N}

Let Rn = Amount in reserve pool when Xn is unbound

Let T = Total unbind fee, in %

Let P = % which goes back to the Reserve Pool (a % of T)

Let D = Doki Buyback (a % of T)

Let A = Azuki Required to Unbind

Let F(Xn) be the function to compute the redeemed value for the nth NFT Unbound

Thus, we have:

F(Xn) = Rn*(1/(N-n+1))*(1-T)

Where Rn = Rn-₁ — (F(Xn-₁))

Let B(Xn) be the function to compute the $DOKI buyback value for the nth NFT unbound

Thus, we have:

B(Xn) = Rn*(1/(N-n+1))*(D)

As there is only one rarity tier in this simplified example, the amount of Azuki burned is a linear function. A*n.

Let’s run through a basic example (excluding Doki Buyback aspect) using real numbers:

Assumptions: R=$40, N=4, P=10%

1st Unbind = 40 x (1/4) x (0.9) = 9

2nd Unbind = (40–9) x (1/3) x 0.9 = 9.3

3rd Unbind = (40–9–9.3) x (1/2) x 0.9 = 9.76

Last Unbind = (40–9–9.3–9.76) x 1 = 11.94 (no unbind fee for the last NFT)

9 + 9.3 + 9.76 + 11.94 = $40 = R = Initial Reserve Pool

Next, let’s check out some graphs which help us visualize the relationship between the number of NFTs Unbound over time, their ever-increasing redemption value, as well as the added value to $DOKI and $AZUKI.

Assumptions: R= 20m USD, N=2000, T=15%, P=10%, D=5%, A=200

After completion of the LGE, we will be able to compute the value of R (Reserve Pool). We will then plug in R into a model, which will suggest to us the optimal value for N (Total number of NFTs), as well as the amount of $BND tokens per roll on the Gacha. The values for T (Total Unbind Fees), P (% which goes back to reserve pool) and D (% for $DOKI buyback) are fixed at 15%, 10%, and 5% respectively. Constant A ($AZUKI required to unbind) will vary depending on the rarity tier of the NFT.

Through the above mechanics, the Chainbinders NFT set appreciates in value over time as:

  1. NFTs become more scarce, since Unbinding burns them forever
  2. With each Unbind, a portion of the extracted value goes back to the the Reserve Pool, increasing the redeemable value of every other Chainbinders NFTs
  3. Ethereum price gains, which increases the value of the Reserve pool in USD terms

Thus we can clearly observe that Chainbinders is the ultimate test of strong hands! There will always be on-demand liquidity, and those who hold onto their NFTs are rewarded. The gacha and unbind contracts will be hosted on PolygonL2, which means that the gas cost is zero! It’s also worth mentioning that the larger the initial reserve pool, the more rewarding it becomes for everyone. Tell your friends!

A shout out to our brilliant developer Kaki for developing the smart contracts to make this happen!

Now, back to Roy ^^.

Card Rarity

The rarity of the card in question denotes the percentage of the Reserve Pool that is redeemable during an Unbinding. Most rare of all are the Chainbinders themselves, individuals seeking a bond with a Collector they can trust. A Collector can sever this bond and Unbind them however, gaining their powers in-lore and a large amount of Ethereum in the real world. This Unbinding process also kills the Chainbinder. There are a very limited amount of Chainbinders, making the acquisition of these characters exceedingly rare. Pray to RNGesus you can find one!

Liquidity Generation Event

During the 21 days of the LGE, BND will be priced in accordance with a stepped Bonding Curve, similar to other crypto LGEs. We have designed a system that is fair for all, but also rewards early investors. BND will be priced at 5$ per token at the start of the curve and top out at 15$, a 3x increase. As a comparison, Hashmasks had a bonding curve that started at 200$ per Hashmask and increased 1000x to 200’000$. We think these sorts of curves are unfair to players who are looking to enjoy the experience, and so we have flattened the curve heavily (3x difference vs 1000x).

There will be no hard-cap to the LGE, meaning as more players mint BND, the Reserve Pool increases overall.

Token Utility

Finally, we have implemented the home currencies of Doki Doki, giving them value and utility in line with their respective roles.


  • 5% of the LGE raise will be used to buyback DOKI and reward stakers
  • 5% of Ethereum generated from Unbindings will be used to buyback DOKI and reward stakers
  • The buyback increases in absolute terms in accordance with the amount of total ETH minted.


  • There will be a nominal requirement of $AZUKI in order to Unbind any Chainbinders NFT.
  • All $AZUKI utilized for Unbinding will be burned forever
  • The total amount of $AZUKI burned increases with the amount of ETH raised during the LGE.

$BND holders will benefit as the token is hyper deflationary, meaning supply becomes more scarce over time. Additionally, $BND can be considered like unopened 1st edition Pokemon packs. A user could in theory, hold his $BND for a year and observe the Reserve Pool increase in price in tandem with Ethereum’s price rise. As $BND will be required to play the gacha machine, the price of $BND should eventually become a function of the remaining redeemable NFTs in the Gacha machine, with a premium.


The Chainbinders Gacha machine will be activated shortly after BND becomes tradeable. We plan to wait several days before turning it on to give users time to trade their BND and allow a market to develop. We hope that Chainbinders delivers on a truly fleshed out experience, with fully realized characters, art, music, and one-of-a-kind mechanics that accompany these rare NFTs. We’re excited to see what this experiment achieves.

The gathering storm is here!


Chainbinders Website :

Doki Doki:



Chainbinders Twitter:

Doki Twitter:

Doki_JP Twitter:



Doki Doki

The NFT Gacha platform. Make collecting fun and inspire digital creations.