On 23/03/18 in the evening I got a PGP encrypted email with an invitation to a challenge involving two ethereum smart contracts called "The Cyber". I was intrigued and spent a bit of time solving the "GateKeeper" puzzles to enter the challenge. Now I would like to share it with whomever else wants to try solving it.
Below is the original message I got -- minus the passphrases.
Hello
You have been formally invited to join theCyber, a decentralized club on the Ethereum blockchain. The contract (thecyber.eth | 0x97A99C819544AD0617F48379840941eFbe1bfAE1) is straightforward by design and deliberately avoids equity memberships, dues, contract ownership or migration, and voting or other governance. Rather, theCyber is intended to operate as a testbed that its members can use to communicate, attend events, and collaborate.