1.CodexSinaiticus(https://www.codexsinaiticus.org/en/)2.NationalCipherChallenge(https://www.cipherchallenge.org/)3.MysteryEnvelope(https://mysteryenvelope.com/)4.RiddleMeThis(https://www.riddlemethis.
1. Codex Sinaiticus (https://www.codexsinaiticus.org/en/)
2. National Cipher Challenge (https://www.cipherchallenge.org/)
3. Mystery Envelope (https://mysteryenvelope.com/)
4. Riddle Me This (https://www.riddlemethis.co.uk/)
5. Cryptogram Puzzle Post (https://www.cryptogrampuzzlepost.com/)
6. Mystery Escape Room (https://mysteryescaperoom.com/)
7. Escape Room Mystery (https://escaperoommystery.com/)
8. Breakout EDU (https://www.breakoutedu.com/)
9. Crack the Code (https://www.crackthecodeescape.com/)
10. The Mystery League (https://www.mysteryleague.com/)