Layer 2 Blockchains for Videogames

As of July 2023, blockchains are becoming increasingly popular, and they are starting to be used in many different fields.

Videogaming is one such field.

In this report it will be explored:

How a blockchain can be used in the world of videogames
Why more scalable layer 2 blockchains are needed
What are rollups and why they are particularly well suited for videogames
What is Starknet and how to deploy a smart contract on it
A simple implementation of a Starknet smart contract to open loot boxes in a completely transparent way (and a demo client to use this smart contract)

Table of contents

Part I - Blockchain concepts and their limitations

What is a blockchain 5
- Transactions
- Miners
- Proof of work
- Journey of a transaction
- Blockchain programmability
- Tokens
Why blockchain can be used in videogames
Why blockchain cannot be used in videogames

Part II - Blockchain: layer 2

Off-chain state channels 12
- State channels and videogames
Sidechains
Rollups
- Optimistic rollups
  - Entering an optimistic rollup
  - Exiting an optimistic rollup
  - L2 - L1 interaction
  - Optimistic rollups and videogames
- Zero-knowledge rollups
  - Entering a ZK rollup
  - Exiting a ZK rollup
  - L2 - L1 interaction
  - Intuition on the validity proofs
  - ZK rollups and videogames

Part III - Starknet

Account abstraction
Starknet actors
- Sequencers
- Provers
- Nodes
Transaction journey
Starknet setup
- Prerequisites
- Install Python3.9
- Install Cairo and Starknet
- Setting up environment variables
- Creating an account
- Deploying and interacting with a smart contract
Cairo
- General concepts
- Storage
- Contract sections

Part - IV - Implementation: immutable loot boxes

Problem statement
The smart contract
The client

Part V - Appendix

Merkle trees
- Merkle proof