Case Study

NFT Trait Upgrade and Survivor Pool Smart Contract


To design and implement a custom smart contract solution that allows NFT owners to participate in a dynamic, game-like experience, giving them opportunities to enhance their NFTs and win Ethereum. The Grumbies NFT project is a unique amalgamation of gaming and NFT collection. When an NFT is first minted, it starts with a basic set of traits. A portion of the initial minting cost contributes to a prize pool, setting the stage for an immersive user engagement experience. Post-minting, we introduced the Trait Bazaar – a marketplace where holders could enhance their Grumbies by purchasing upgradable traits. This not only altered the aesthetics of the NFT but also dynamically updated its metadata.

NFT Trait Upgrade and Survivor Pool Smart Contract

The Challenge

Dynamic Trait Integration: One of the central features of Grumbies was the dynamic updating of NFT traits. Crafting a system that could seamlessly handle on-chain updates to both the visual and metadata components of an NFT without causing disruptions was a technical hurdle.

Economic Balancing: The financial mechanics of routing sales into the prize pool, while ensuring sustainable support for the project team and artists, demanded meticulous planning. Finding the right balance to keep both holders and creators satisfied was paramount.

Chainlink VRF Integration: Ensuring a genuinely randomized, yet verifiable, trait elimination process posed challenges. Implementing Chainlink's VRF, while ensuring its compatibility with our smart contract's design, required careful calibration.

User Experience & Engagement: Creating a continuous engagement model, especially in a market flooded with numerous NFT projects, was crucial. The team needed to ensure that the game-like structure of Grumbies was not just novel, but also intuitive and captivating for holders.

Security Concerns: With dynamic trait updates and direct Ethereum claims from the contract, ensuring top-notch security to prevent any vulnerabilities or potential exploits was a non-negotiable imperative.

Scalability & Performance: As the project attracted more users, ensuring that the smart contract could handle a high number of simultaneous trait upgrades and Ethereum claims without latency or failures was a key concern.

Addressing these challenges head-on, the Metaseed Labs team worked tirelessly to provide solutions, ensuring that Grumbies not only functioned flawlessly but also stood out as a premier NFT project in the blockchain space.

How we solved the problem

NFT Trait Upgrade and Survivor Pool Smart Contract

The Solution

The Grumbies NFT project showcased the extensive capabilities of Metaseed Labs in creating a custom smart contract and delivering an unparalleled Web3 experience. Not only did participants enjoy the aesthetics of their evolving NFTs, but the gamified element also drove consistent engagement, further adding value to their holdings.

Grumbies stands as a testament to our ability to transform conventional NFT projects into dynamic, interactive platforms, intertwining the allure of gaming with the tangible benefits of decentralized assets.

Trait Dynamics: After the full minting phase, 25% of the funds were utilized to seed the prize pool. In the Trait Bazaar, Grumbies holders could upgrade traits from categories such as headgear and outfits. This dynamic change not only enhanced the NFT visually but also increased the holder's potential rewards. The rarer the traits, the higher the chances of winning Ethereum.

Financial Flow: Trait sales contributed directly to the prize pool. Specifically, 70% of the trait sales were directed into the pool, while the remaining 30% supported the project team and the artists behind Grumbies.

Chainlink VRF Integration: A pivotal part of the project was the random elimination of traits. Using Chainlink's Verifiable Random Function (VRF), a trait was randomly picked and eliminated from the survival pool at intervals. The system was designed to favor rarer traits, giving them a lower probability of elimination.

Winning Mechanics: To remain in contention for the Ethereum prize, a holder's Grumbies needed to retain at least one non-eliminated trait. When only 10 (or fewer) traits remained, the game concluded. At this point, all holders with non-eliminated traits could stake their claim on their proportional share of the Ethereum prize pool, directly and trustlessly via the smart contract.

Client testimonial

"Engaging with Grumbies was truly a game-changer in the Web3 NFT arena. Its innovative dynamics offered not just an NFT, but an exhilarating and unique experience. Amidst the myriad of projects out there, Grumbies was a refreshing and delightful breath of fresh air!"