Symble is a logic game where you have to crack 4-digit passwords. To do this, you must create a password that will allow you to access the password's protected value. You are given a prompt, and then you have to find the correct answer from various possibilities presented in the prompt.
This is one of those games that can be addictive once you start playing it. The later levels get more challenging as well so it's best if you spend some time figuring them out before starting your adventure. Good luck!