MetaSoccer Integrates Chainlink VRF to Unlock Provably Random NFT Minting

4 min readMar 3, 2022

In another huge technical milestone for our soccer metaverse, MetaSoccer is excited to announce that we have integrated Chainlink Verifiable Random Function (VRF) on Polygon mainnet. By integrating the industry-leading decentralized oracle network, we now have access to an auditable and tamper-proof source of randomness that can help generate provably random attributes in our Scout NFT collection. Chainlink VRF helps ensure that we are building out a game underpinned by fairness and transparency.

Verifiable randomness is particularly important when it comes to the redemption of both pioneer and standard Scout tickets. When users mint Scout NFTs, MetaSoccer creates a randomness request with Chainlink VRF to help determine the random number of the NFT. Afterward, we use this number as well as the properties of the redeemed ticket to calculate the initial Scout attribute in a verifiably random process.

In order to randomize NFT attributes in a fair manner, we needed access to a secure random number generator (RNG) that any user could independently audit. However, RNG solutions for smart contracts require several security considerations to prevent manipulation and ensure system integrity. For instance, RNG solutions derived from blockchain data like block hashes can be exploited by miners/validators, while off-chain RNG solutions derived from off-chain APIs are opaque and don’t provide users with definitive proof about the integrity of the process.

“Generating Attributes”

After reviewing various solutions, we selected Chainlink VRF because it’s based on cutting-edge academic research, supported by a time-tested oracle network, and secured through the generation and on-chain verification of cryptographic proofs that prove the integrity of each random number supplied to smart contracts.

Chainlink VRF works by combining block data that is still unknown when the request is made with the oracle node’s pre-committed private key to generate both a random number and a cryptographic proof. The MetaSoccer smart contract will only accept the random number input if it has a valid cryptographic proof, and the cryptographic proof can only be generated if the VRF process is tamper-proof. This provides our users with automated and verifiable assurances directly on-chain that Pioneer and Scout NFT attributes are determined in a provably fair manner and the random number generator has not been tampered with by the oracle, outside entities, or the MetaSoccer team.

We’ll also be using Chainlink VRF to generate Players in the future. When the Scout returns from scouting, a random value will be used as the entropy for the whole scouting process, including scout improvements. The attributes of the Scout at the precise moment of scouting will then be used alongside the Chainlink VRF-generated random number to calculate the starting attributes of Players.

As a next step, we also plan to launch mystery boxes that also leverage Chainlink VRF, giving our users high assurances of provably unbiased rewards distribution.

“To be the best soccer metaverse ecosystem — an unrivaled force and industry leader — we need to make sure that our processes are tamper-proof. There should be no avenues to interfere or manipulate any function, and every aspect of the metaverse should be unapologetically fair, equal, and transparent. That’s the innate spirit of GameFi. Our integration of Chainlink VRF undergirds all of MetaSoccer’s randomness functions, helping us make an incremental step to reaching our ultimate goal.” — Marc Cercós, CEO and Co-Founder of Champion Games, the game studio behind MetaSoccer.

About MetaSoccer

MetaSoccer is the first blockchain-based soccer metaverse where users can create their own club and generate income while playing (Play-to-Earn).

A whole soccer ecosystem where users can participate full-time as club owners or managers while having fun and generating income. MetaSoccer embraces multiple revenue streams such as: NFT asset drops, fees from different transactions across the ecosystem (marketplace sales, betting, token swap…), sponsorships and broadcasting.

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About Chainlink

Chainlink is the industry standard for building, accessing, and selling oracle services needed to power hybrid smart contracts on any blockchain. Chainlink oracle networks provide smart contracts with a way to reliably connect to any external API and leverage secure off-chain computations for enabling feature-rich applications. Chainlink currently secures tens of billions of dollars across DeFi, insurance, gaming, and other major industries, and offers global enterprises and leading data providers a universal gateway to all blockchains.

Learn more about Chainlink by visiting or reading the developer documentation at To discuss an integration, reach out to an expert.




MetaSoccer is the first soccer metaverse where users can manage their own club and generate income while playing