Code Runner

Outrun null, undefined, NaN and runtime bugs in this endless runner for developers. Jump the obstacles, go the distance, built with Canvas 2D and zero dependencies.

📅

Avoid: jump them!

  • nullnull referencegame over
  • undefinedundefinedgame over
  • NaNnot a numbergame over
  • 🐛runtime buggame over

Controls

  • Space / ↑ / Clickjumpdesktop
  • Tapjumpmobile
  • Space / Tapstart / restartmenus
Your best score0

What is Code Runner?

Code Runner is an endless runner arcade game for developers. You sprint along a terminal floor while the classic runtime hazards rush toward you: null, undefined, NaN, and the occasional 🐛. One well timed jump clears each one. Miss the timing and you throw an uncaught exception.

It is built with the HTML5 Canvas API and zero external dependencies, so it runs instantly on desktop and mobile, no install, no signup.

Game features

  • One button: Space, arrow up, click, or tap to jump.
  • Speed ramp: the run gets faster the further you go.
  • Distance scoring: your meters become your score.
  • High score tracking: best distance saved locally across reloads.
  • Share your run: challenge other developers in one click.

How to play

  1. Press Space or tap to start running.
  2. Jump over null, undefined, NaN, and bugs.
  3. The longer you survive, the faster it gets.
  4. Crash and press Space or tap to run again.

A fast, addictive coding break that fits in the time it takes a test suite to finish.

Frequently Asked Questions

How do I play Code Runner?

Press Space, the up arrow, W, click or tap to start and to jump. You can only jump while on the ground, so time each jump for the null, undefined, NaN and bug obstacles rushing toward you.

How is the score calculated?

Your score is the distance run divided by 20, shown as distance in the HUD. The run speeds up with distance until it reaches the maximum, and the gaps between obstacles are random within a range so you cannot memorise a pattern.

Is my best distance saved?

Yes, the best distance is stored in your browser localStorage on that device. There is no account and nothing is uploaded.

Does it work on mobile?

Yes. The board scales to the screen width and a tap anywhere on it jumps. The keyboard shortcuts only apply while the board is on screen, so the article below still scrolls normally.