18 challenges I've written. Each has its own tutorial post and locally hosted files. The offline challenges have local flag checks. You can also read the JSON catalog, or each challenge's plain-text and JSON versions.

2025

• Challenge archive: SekaiCTF 2025 - Law and Order

2024

• Challenge archive: Google CTF 2024 - desfunctional
• Challenge archive: Google CTF 2024 - IDEA
• Challenge archive: Google CTF 2024 - McEliece - offline
• Challenge archive: SekaiCTF 2024 - Some Trick - offline

2023

• Challenge archive: HTB Cyber Apocalypse 2023 - Blokechain
• Challenge archive: SekaiCTF 2023 - Diffecientwo
• Challenge archive: SekaiCTF 2023 - RandSubWare

2022

• Challenge archive: SekaiCTF 2022 - Diffecient
• Challenge archive: SekaiCTF 2022 - FaILProof - offline
• Challenge archive: SekaiCTF 2022 - FaILProof Revenge - offline

2021

• Challenge archive: zh3r0 CTF V2 2021 - 1n_jection - offline
• Challenge archive: zh3r0 CTF V2 2021 - b00tleg
• Challenge archive: zh3r0 CTF V2 2021 - chaos
• Challenge archive: zh3r0 CTF V2 2021 - cheater mind (Miscellaneous)
• Challenge archive: zh3r0 CTF V2 2021 - import numpy as MT - offline
• Challenge archive: zh3r0 CTF V2 2021 - real_mersenne
• Challenge archive: zh3r0 CTF V2 2021 - twist_and_shout - offline

Practice challenges

These have their own flags and local checks.

• Flag checker introduction
• Injection
• Wiki Mersenne
• Untwist Me
• Mersenne seed recovery

Your saved practice progress