About Debug Dungeon
A free debugging practice game. Broken code, real error messages. Find the bug and choose the right fix to defeat each monster.
Skills you practise
- Reading errors
- Debugging
- Python / JS / C
How to play
- Read the code and the error message.
- Find the faulty line.
- Pick the correct fix.
Why this skill matters
Developers and support engineers spend a large share of their time reading error messages and fixing broken code. The skill is not guessing: it is reading what the message says, finding the line, forming a likely cause and testing a fix. This game gives you small broken programs and real-looking errors to practise that loop. It is a free way to practise debugging for beginners and to get used to reading Python, JavaScript and C error messages before they show up in your own projects.
Key terms you will meet
- Bug
- A mistake in code that makes it behave in the wrong way.
- Syntax error
- The code breaks the language's grammar, such as a missing bracket or colon, so it cannot run.
- Runtime error
- The code starts but fails while running, for example dividing by zero.
- Logic error
- The code runs without errors but gives the wrong answer.
- Stack trace
- The list of steps leading to an error. The last lines usually point to the file and line that failed.
- Print debugging
- Printing values at points in the program to see what is really happening.
A worked example
A program prints IndexError: list index out of range. You read the message and see the code asks for item 5 of a list that has only three items, positions 0, 1 and 2. The fix is to use a valid position or loop over the list. The game explains why the other tempting options, like reinstalling the language, would not help.
Common mistakes to avoid
- Ignoring the error message and changing code at random.
- Forgetting that lists and many counters start at 0.
- Fixing the symptom in one place while the cause is somewhere earlier.
Questions people ask
What should I do first when I see an error?
Read the message from the bottom of the trace, note the file and line number, and think about what the code expected versus what it got.
Is debugging the same in every language?
The method is the same. The wording of error messages differs between languages.
How do I get better at fixing bugs in my code?
Practise on many small broken programs rather than one big project. For each one, read the error message, find the line it points to, guess one likely cause and test a single change. Debug Dungeon trains exactly that loop with real-looking errors.
Level: Intermediate · Best for: Programming students · Part of the Programming & CLI path. Pass it to earn the “Debug Dungeon Master” badge and a game certificate.
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Content reviewed by Hritik · 2026-11-11.