A code-guessing game for Octojam 2021 written in the Octo assembly language for Chip-8.

You play a safecracker with 12 chances to guess a 4-digit passcode. Luckily for you, your tools and flaws in the safe will make it easier.

A live version can be played on itch.io with optional touch or mouse controls. Click or tap the running game to enable the keypad.

If you don't play the web version, this game requires a Chip-8 implementation that that supports XO-Chip v1.0 instructions, such as Octo.

You can run Octo in the browser and paste the code in, or use another emulator with full XO-Chip support such as c-octo (requires knowledge of how to build from C source).

Your goal is to guess a 4-digit passcode in 12 tries or fewer. Your current guess is the rightmost column of numbers.

The passcode will not use a digit more than once. If the currently passcode guess repeats digits, an "X" will be displayed above it, and you won't be able to submit it. A valid passcode will display "OK" above it. Decreasing or increasing a digit past 0 or 9 will wrap around to the other side.

After every guess, you will see feedback above it using up to four dots:

• Every dark dot represents a digit in the correct location
• Every light dot represents a digit that is somewhere in the passcode, but currently in the wrong place
• Fewer than four dots means that not all of the digits in your guess are in the passcode
• 0 dots mean that none of the digits you guessed are in the code

After the 12th guess, the game is over, and you win or lose. You can win earlier than the 12th guess if you deduce the passcode early.

Use the following keys to play the game:

The font included is based on Tom Thumb, which is used under CC0 Public Domain Dedication.

There is no sound at release time.