Turning a legacy mobile game into a 'blockchain-based' game

A look at Candy Crush Saga.

Before we start, I have to acknowledge that this article’s title is a bit of a misnomer. What is a blockchain-based game? These are sad times when technology is valued more for hype than for its value to fulfill use cases. Somehow regular games are not as cool anymore (or they are harder to get funding for), and thus we need to make blockchain-based or blockchain-enabled games now, regardless of which functionality the blockchainability actually provides.

A perhaps more fitting title could be: ‘Adding a P2E blockchain gameplay meta-layer to an existing legacy mobile game.’


This case study is an exploration of turning a legacy mobile casual game into a ‘blockchain-based’ game. I chose to look at Candy Crush Saga for a number of reasons:

  • Hypercasual or casual games that studios monetize with ads aren’t a good target for NFTs;
  • Freemium games that studios monetize via IAPs synergize well with NFTs;
  • Freemium games monetized via IAPs already have a base reward economy that better supports adding a blockchain meta-layer;
  • I wanted something familiar, without a learning curve and a mass-market demographic;
  • Candy Crush Saga is the top-grossing game that ticks all the boxes above.
Figure 1. $73+ million in revenue in the last 4 weeks. Candy Crush Saga was first released in 2012.

Is my adaptation play to earn?

Players can acquire digital assets worth real money, but that is true for casino games, and we don’t call those P2E.

Although the ‘play to earn’ moniker helps pitch games (to both investors and players), games that don’t rely on traditional monetization mechanisms can’t predictably sustain their economy without a pyramid scheme. Players need to exchange value (typically via buying IAPs, betting against other players, or watching ads) for the economy to be sustainable in the long run. The value that a player receives needs to come from somewhere.

Thus, when architecting blockchain-based game economies, consider where the value originates. For example, do players play for free and cash out their earnings? If so, then the value comes from players buying in.

In those cases, the psychology of buying tokens is more akin to purchasing company equity than buying an in-game currency.

The players who earned massively on those games were essentially rewarded for being early adopters and had access to ROI rates that aren’t sustainable in the medium term. We should not expect such rates when releasing new blockchain-based games unless the token has superb utility or if a well-renowned legacy company released it - e.g., Ubisoft token, FIFA token.

Therefore, in my adaptation of Candy Crush Saga, the game has two modes:

  • Casual mode - play for fun, earn residual amounts of in-game currency (a token)
  • Competitive mode - play against other players, bet tokens, and acquire NFTs from loot boxes. In timed leaderboards (daily, weekly).

Furthermore, the player can also:

  1. Stake tokens to earn more tokens
  2. Buy IAPs and get equivalent NFTs
  3. NFT marketplace - a website where players can trade items.

Suggested game adjustment

In terms of gameplay, there is no adjustment. Instead, the adaptation relies on a meta-game layer that functions more or less independently of the legacy game. Some functionalities that the studio would need to implement:

  • In-app wallet integration (metamask);
  • Backend webhook services to reward players with NFTs when they earn/buy IAPs and in-game currency;
  • Web interfaces to earn and collect loot boxes.


Figure 2. Game Economy Diagram

First off, we need to consider the legacy game’s monetization model. Candy Crush Saga is a Freemium game. King (Candy Crush Saga’s publisher) makes money from players who spend money to buy IAPs.

Players solve puzzles of increasing difficulty while faced with certain limitations, for example, the number of lives they can dispense with attempting to solve a puzzle.

The game’s revenue model relies on selling booster items to make things easier or keep playing.

Reward token

Retrying a puzzle after failing to solve it involves either waiting for lives to be replenished or purchasing an IAP with an in-game currency called ‘Gold Bars.’

So the first adaptation we’re going to make is to turn ‘Gold Bars’ into a token.

A server-side service will listen on a webhook to events from the store and issue a request to mint ‘GoldBars.’

Thus, whenever the player would otherwise receive ‘Gold Bars’ as a reward or buy them as IAPs, they get ‘GoldBars’ instead.


Nearly all IAPs in Candy Crush Saga are consumable. Consumable IAPs aren’t very practical to turn into NFTs. So we will keep it simple and create some new IAPs that support our blockchain economy:

  • NFTs that increase the amount of staking you get
  • NFTs that multiply ‘Gold Bar’ earnings
  • Aesthetic NFTs that make you look cool and allow you to show off to opponents
  • NFTs that give players access to levels where they can bet more in competitive mode

We need another token - The Utility Token

We need another token for reasons we don’t have time to cover here. It’s the utility token. Let’s call it KingCoin and set a fixed supply of 100M.

Players will receive most rewards in the Reward Token (GoldBars). They can also directly buy Gold Bars in-game as an IAP. Therefore GoldBar Tokens have an infinite supply.

And they will use the Utility Token (KingCoins) to make money by:

  • Staking KingCoins
  • Betting KingCoins (in PVP)

They can also use KingCoins to buy GoldBars.

Figure 3. The game has two tokens

Players can also convert Gold Bars into KingCoins, by staking them in a pool and getting whatever share of KingsCoins that are due to mint in the next 24h period.

Like KingCoins, NFTs that give P2E perks (all except aesthetic NFTs) would also have pre-specified supply limits.

NFT Marketplace for NFTs

An NFT Marketplace is essential to provide players with additional P2E opportunities. In addition, trades within the marketplace bring additional revenue to the Studio since the studio collects royalties on sales.

Optimally, the studio would rely on either an existing marketplace or a marketplace supported by the studio's platform.

Options to curb GoldBars inflation

Since the supply of GoldBars is infinite and the supply of KingCoins is finite, GoldBars will suffer inflation, this is natural and not necessarily a problem. Still, if the studio wants to curb inflation additional strategies can be employed:

  • GoldBars single-sided staking;
  • KingCoin/GoldBars liquidity pair staking;
  • GoldBars burning mechanic.


Figure 4. High-level roadmap. The height of the data points represents how much value the studio can expect to retain at certain times in development.


Legacy games that bring in millions of monthly revenue champion the top charts on the mobile stores. Certain games have consolidated their position and have been there for a long time, some for over a decade.

As blockchain gaming matures, it is natural that these companies introduce a meta-layer on top of existing casual games and re-release them as spinoffs.

I attempted to determine how one such meta-layer could work for Candy Crush Saga in this case study.

Something that became apparent is that for cases where the Company/Studio has multiple titles and good credibility, the company can issue a Platform Token - a unified utility token across games. In this case study, KingCoins are a Platform Token.

I sometimes call this the platform angle. This approach can make it easier for the publishing company to support the token’s valuation. Essentially, the company’s reputation backs the token’s value.