Sanctuary: Building Echelon’s Next-gen NFT Marketplace

ChainSafe Gaming was contracted by Echelon to develop, among other related systems, Sanctuary: the NFT marketplace that will feature tradable NFT assets from Parallel.

Sanctuary: Building Echelon’s Next-gen NFT Marketplace

“It feels collaborative, it feels like we’re both invested in each other’s success. We’ve really enjoyed working with the ChainSafe Gaming team." - Echelon Prime Foundation

  1. Meet Echelon
  2. Echelon marketplace: the blueprints
  3. Building to spec with ChainSafe Gaming
  4. Enhancing games with blockchain
  5. The result: a next-gen web3 marketplace
  6. Working with Chainsafe: Testimonial

A force in web3 gaming, the Echelon Prime Foundation has already turned heads with its first adopted title, Parallel TCG. Their shared sci-fi aesthetic and focus on immersive lore are captivating gaming audiences, positioning both Echelon and Parallel Studios as emerging drivers behind the next generation of web3 games.

ChainSafe Gaming worked with Echelon to develop, among other related systems, Sanctuary: the NFT marketplace that will feature tradable NFT assets from Parallel.

While many web3 games list NFTs on platforms like OpenSea, Parallel will enjoy its own custom, vertical marketplace. From a player’s perspective, this marketplace feels like a continuation of gameplay—complete with Parallel’s specific branding and style.

“Everything that we build has to work and provide value at the core functionality level to our user base, but it also has to feel consistent with that style and artistic vision and design language that [Parallel] has as well that people fell in love with in the first place.” - Echelon Prime Foundation

ChainSafe’s in-game marketplace is a white-label offering that delivers on those intangible factors, such as immersion and feel, that keep players engaged in a game. Have you ever walked through a door and forgot what you were doing? Or perhaps you visited OpenSea from a web3 game and lost track of time browsing NFTs?

This marketplace solves that. Moreover, it captures transactions within your game or platform, preventing lost revenue to a third-party marketplace. We developed some advanced customizations for Echelon that elevate this marketplace and expand players' capabilities.

Sanctuary marketplace, featuring a catalogue of tradable cards from Parallel TCG.

Meet Echelon

The Echelon Prime Foundation is an organization focused on supporting the development of its decentralized, innovative gaming ecosystem. They first announced themselves in January 2022 in the Echelon Whitepaper

While Parallel is the game players will interact with (and the first game partnered with Echelon), Echelon is the governance, token, and infrastructure support system that helps merge blockchain technology with the games in its curated library.

Echelon oversees PRIME, the utility token holders use to unlock novel and next-generation in-game experiences. PRIME also serves as an in-game currency, earned by winning games. 

What is PRIME?

PRIME is a utility token used primarily in PRIME Sinks—products, services, and experiences available for PRIME.

  • In-game currency, earnable through winning matches
  • ERC-20 standard
  • Also used in community governance
  • Launched March 2023 by community vote

Parallel TCG

Parallel TCG by Parallel Studios is a gritty science fiction game that pits players against each other in card-based battles. Parallel is free-to-play and offers NFT versions of each card in the game. Players can generate non-NFT versions of their cards for their decks, called Apparitions.

The concept for Parallel emerged during the pandemic—cooped-up gamer friends, playing games together to pass the time, started playing with the idea of creating something new. Eventually, Parallel’s detailed, intensely gratifying card art and its fascinating narrative made it the game to watch for players both within and without web3.

Echelon marketplace: the blueprints

Echelon and Parallel Studios are specifically focused on developing a smooth, seamless experience for the player:

“What we’re trying to do is solve real problems and come up with innovative technological solutions where they’re improving the user experience. We think a lot of what happens in the crypto world is solutions seeking a problem, and we’re really looking at things [as] ‘what is not working’ and ‘what could be working better.’ ” - Parallel Studios

By bringing on ChainSafe to contribute to this vision, we exercised our expertise and developed an efficient, highly customized product in Parallel’s Sanctuary.

Click to join the waitlist for ChainSafe Gaming's marketplace offering.

Building to spec with ChainSafe Gaming

With a trading card game as the first title in Echelon’s library, there are some bespoke considerations beyond the mechanics of exchange. 

Trading or transacting in the Echelon marketplace is an extension of gameplay and demands as smooth an experience as possible. ChainSafe was responsible for building the trading system, indexing API, Win/Loss API, and front end. Another task was to include economic stipulations in the marketplace smart contracts, such as fee collecting and currency support. 

Let’s look at some of Echelon’s requirements for their marketplace.


  • No division of markets based on currency
  • Simplified trading actions
  • Listings expire after 30 days
  • Automatic currency swaps


  • Card data listing API
  • Process card images for marketplace thumbnails
  • Scalability as the NFT catalogue and market listings increase

User interface 

  • Prominent card art to inspire collectors
  • Seamless marketplace integration with the game (no browser pop-ups)

Enhancing games with blockchain

Capturing the magic of a classic TCG is only part of this marketplace’s design. The Echelon team and creators behind Parallel consider blockchain integrations an opportunity to expand gaming experiences for modern players.

Trading card games are not limited to the play phase—anyone who ever got into Pokémon, Yu-Gi-Oh!, or Magic: The Gathering can attest to this. There’s the collecting experience, visiting a card shop, and immersing yourself in the lore and world beyond gameplay. The Sanctuary marketplace expresses these ambient features for Parallel players through practically every facet of its design.

“Do we want [players’] first experience buying something to be from a non-descript, horizontal marketplace? Or do we want it to feel like it is part of the ecosystem and the lore, and the story that we believe is going to pull people in?” - Echelon Prime Foundation

Card-for-card Swaps is a particularly cool Sanctuary feature that emulates and expands on the traditional TCG experience.

“Swaps” describes the feature succinctly: Parallel players can make card-for-card exchanges with each other. The action is simple enough—a player posts a card they’re offering and the card or cards they want in return. Adding this often nostalgic TCG feature to Echelon's marketplace incorporates a crucial community aspect into web3 gaming's bag of tricks.

Card swapping page, featuring proposed card-for-card trades on Sanctuary.

The result: a next-gen web3 marketplace

Parallel players will enjoy an exquisitely simple trading experience. The Sanctuary marketplace is as fun and intuitive as flipping through your buddy’s Magic card binder. 

Seamless NFT Trading

Smooth user flow is the name of the game. Buying or selling NFT assets is a two-click process: a player clicks Buy or Sell, then once more to confirm the action. A significant benefit of our marketplace is that sellers can post an NFT for sale along with the currency they want to receive, while the buyer completing the trade determines which currency they are looking to spend (or vice versa). If the currencies don’t match, the underlying smart contract handles the conversion seamlessly via Uniswap integration.

Another feature geared to traders’ peace of mind is a 30-day expiry on all listings. This way, players won’t find themselves in a situation where they’ve forgotten about a listing and start scrambling to find their tokens. After expiry, the player’s tokens are returned to their wallet automatically.

Parallel players can transact in ETH, PRIME, or USDC within Sanctuary. Since currency conversions are automatic, all marketplace listings on Sanctuary merge into a vast, undivided catalogue.

Indexers: data communication and NFT discoverability

The Sanctuary marketplace also employs several APIs and an indexer to manage events and NFT information. When a player decides to list an NFT, cancel a listing, or complete a purchase, this is the process that follows:

  1. Indexer fetches the events (item listed/item purchased, item cancelled) from RPC nodes.
  2. The indexer parses the event’s data and stores it in the database.
  3. A Graphql API server is exposed, which returns data based on the query from the database.

The indexer API allows players to sort or filter marketplace listings based on NFT attributes, which are present in the NFT's metadata. In Parallel, this data includes the card name, description, and play-specific attributes such as class, rating, parallel (like a faction, or red, white, etc. for Magic players), and so on. 

Additionally, the indexer accesses each NFT’s metadata to provide card artwork to the UI. Because only the full-resolution version of the NFT exists in its JSON file, the indexer performs the image resizing necessary for thumbnail renderings in the marketplace.

Overall, it’s fast. The marketplace performs exceptionally well, and ChainSafe continues to develop solutions for Echelon to ensure that performance scales alongside their NFT library and projected number of trade listings. Parallel players will enjoy a next-gen web3 experience, and we couldn’t be happier to have built such a core component to a truly outstanding game.

Game data: win/loss API

For Parallel Studios, ChainSafe Gaming built an API data feed that collects win/loss information from each game of Parallel. While not yet deployed at the time of this writing, this component has the potential to power some very cool features built on top of the game in the future.

Once deployed, the Win/Loss API will allow Parallel to send daily, automated messages to ChainSafe containing a dataset with the win/loss record of every game played in the previous 24 hours. This data is made immutable and searchable via CID by uploading it to IPFS via ChainSafe Storage.

Working with ChainSafe: Testimonial

ChainSafe dedicated a highly skilled and efficient team of engineers full-time to build Echelon’s custom marketplace. By keeping the team agile and focusing entirely on Echelon’s product, we could stay in frequent communication with Echelon and adapt to the unexpected, ultimately delivering a high-quality product.

Feedback from Echelon:

"ChainSafe is really good about being upfront, laying out potential solutions, treating it like a partnership instead of just a job…

Feeling like the people that we’re working with are also invested in our success, it’s how I would approach it…

ChainSafe just did a good job both adapting and keeping us in the loop.” 

Click to join the waitlist for ChainSafe Gaming's marketplace offering.


Thank you to the Echelon Prime Foundation and Parallel Studios for contributing via interview.

Thank you to the ChainSafe team members contributing to this article:

  • Tetyana B., Senior Solidity Engineer
  • Sadiqur Rahman, Senior Engineer
  • Colin Schwartz, Product Manager

Team contributions

These team members contributed to building this product:

  • Filip Štoković
  • Igor Ko
  • Tetyana Bushenyova
  • Anderson Lee
  • Ohm Patel
  • Sadiqur Rahman Sohel
  • Arun Dhyani