Decrypt the message: 7y9rr177sluqv1r4pw
This task was an easy fun challenge. Due to a small mistake, the first hint was not given at the start (sorry guys) and it was pure guessing. The actual categories percentage for the task were 20% crypto and 80% ucucuga (ucucuga means guessing). So those who opened the task should have been aware of that.
Even after the first hint there were no solutions, so the next hint was released:
bash$ at. It was a straight pointer to the atbash cipher, where every character maps to the same one in the reversed alphabet (a -> z, b -> y, etc.). Here it was slightly modified – the numbers were added to the alphabet: a-z0-9.
The key is classiccryptoisfun.