Challenge Overview
How about some hide and seek heh?
Look at this image here.
Solution
wget https://artifacts.picoctf.net/c/237/atbash.jpg
Based on the name of the image it is probably decoding with atbash.
To get the extracted string from the image just run steghide without any passphrase.
steghide extract -sf atbash.jpg
From there I just did cat encrypted.txt and plugged it into cyberchef with the atbash cipher.
Flag: picoCTF{atbash_crack_05...}