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Stupid Mario

I have seen a bunch of neural network articles around Hacker News lately. The way I boiled it down was: if you could simplify a problem and solution down to a finite number of inputs and a binary output, you could train a network to solve that problem on its own.

I used to do a lot of Mario speed runs in high school. I was never any good, but to this day that is the only way I can play Mario now. It has been ingrained into my muscle memory.

What if I taught a neural network how to play Mario?


Starting simple. I just want to see if I can train a network to NOT DIE. I will ask the network when to jump throughout the level. After so many experiences dying where he should jump, hopefully he will learn to jump.


I used the fantastic JSNES to facilitate the game itself. I was able to easily grab the data I needed directly from the emulator's memory. I found this great map that made it easy to find the exact variables I used for training and event detection.

The next part was the brain itself.

I tried quite a few big open source neural network Javascript libraries, but due to development issues, I decided to just use a simple perceptron function.


I wanted to training to be just like a human, visual. So my training input was a normalized frame buffer which I converted to greyscale for ease of use with the perceptron.

The output would be if Mario needed to jump right after that frame.

I simply trained the perceptron by detecting when Mario had died and used the previous buffer.

Automating the game play was the trickiest part. I had to detect game overs, collision deaths, and pit fall deaths, and automate Mario's controls.


No, I do not have a perfect Mario player yet… that is why I titled this post Stupid Mario.

It is hard to truly tell if a network is learning until it makes sufficient progress.

Try it out!

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