Suggested improvements

[NZSmartie]

I did most of the challenges on a mobile phone using Nordic's nRF Connect. Reading the first hint, it said to send a payload to a specific handle? Which was confusing until I realsied it was specific to Linux and how gatttool works.

Instead, may I suggest you introduce the concept of UUIDs and how each characteristic on a service has incrementing numbers based on the Services' UUID?

A new flag idea wcould be to challenge the player to identify a 16bit UUID and send a payload that conforms to that standard, Like setting the time with a UUID of 0x1805 (Current Time Service)

You could use that as an opportunity to perform OSINT on GATT UUIDs.

Another idea is to set up a BLE beacon and using a tool like RamBLE to locate the beacon and read the flag from the advertised data.

[NZSmartie]

If you like these ideas, i may be able to do a PR for you once i've got some free time