Here are my solutions to the Ethernaut Challenges. Please note challenge #1 through #11 were solved using Remix so the solutions are in the form of Solidity contracts. Challenge #12 and beyond were done using Hardhat and so their solutions appear as Ethers.js test cases.
Happy bug hunting!
https://aaruni.io/2022/08/ethernaut-solutions-1-fallback
https://aaruni.io/2022/08/ethernaut-solutions-2-fallout
https://aaruni.io/2022/08/ethernaut-solutions-3-coinflip
https://aaruni.io/2022/08/ethernaut-solutions-4-telephone
https://aaruni.io/2022/08/ethernaut-solutions-5-token
https://aaruni.io/2022/08/ethernaut-solutions-6-delegation
https://aaruni.io/2022/08/ethernaut-solutions-7-force
https://aaruni.io/2022/08/ethernaut-solutions-8-vault
https://aaruni.io/2022/08/ethernaut-solutions-9-king
https://aaruni.io/2022/08/ethernaut-solutions-10-re-entrancy
https://aaruni.io/2022/08/ethernaut-solutions-11-elevator
https://aaruni.io/2022/08/ethernaut-solutions-12-privacy
https://aaruni.io/2022/08/ethernaut-solutions-13-gatekeeper-one
https://aaruni.io/2022/08/ethernaut-solutions-14-gatekeeper-two
https://aaruni.io/2022/08/ethernaut-solutions-15-naughtcoin/
https://aaruni.io/2022/08/ethernaut-solutions-16-preservation/
https://aaruni.io/2022/08/ethernaut-solutions-17-recovery/
https://aaruni.io/2022/08/ethernaut-solutions-18-magicnumber/
https://aaruni.io/2022/09/ethernaut-solutions-19-alien-codex/
https://aaruni.io/2022/09/ethernaut-solutions-20-denial/
https://aaruni.io/2022/09/ethernaut-solutions-21-shop/
https://aaruni.io/2022/09/ethernaut-solutions-22-dex/
https://aaruni.io/2022/09/ethernaut-solutions-23-dextwo/
https://aaruni.io/2022/12/ethernaut-solutions-24-puzzle-wallet/
https://aaruni.io/2022/12/ethernaut-solutions-25-motorbike/
https://aaruni.io/2022/12/ethernaut-solutions-26-doubleentrypoint/
https://aaruni.io/2022/12/ethernaut-solutions-27-good-samaritan/