Need help with hacking Elevator Action

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Paul92
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Joined: Mon Dec 27, 2021 7:26 pm

Need help with hacking Elevator Action

Post by Paul92 »

Hi all

I was wondering if it is posisble to hack Elevator action so that the gangsters are able to shoot each other if they are caught in the crossfire It will give it a more comical effect. I don't need to edit any graphics, which is more or less what is more common in the NES hacking community, all I need to do is to change the code so that the existing graphics work slightly differently.

Thanks
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Memblers
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Re: Need help with hacking Elevator Action

Post by Memblers »

Possible yeah, but probably not easy. Hit detection can be CPU-intensive, so it's likely designed around the cases they needed. Detecting hits of all the enemies bullets against one player, or detecting one player's bullets against all the enemies. Adding in hit detects for all the enemy bullets against all the enemies could become a big CPU load.

The idea is pretty funny.
Paul92
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Joined: Mon Dec 27, 2021 7:26 pm

Re: Need help with hacking Elevator Action

Post by Paul92 »

Always up for a bit of a challenge, unfortunately I have zero coding knowledge so would need to be coached how to do it.

So please explain more of this hit detection.

I have access to an oracle cloud trial, with $400 to throw at something with a high CPU amount to make things a little easier. If that's needed.
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Ben Boldt
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Re: Need help with hacking Elevator Action

Post by Ben Boldt »

Here is how I would approach this. Different people may have different methods/ideas.

Run the game in FCEUx with code/data logging turned on, and play the game for as long as you can without taking any damage. Then open the trace logger and check "only log newly mapped code" and log it to a file. Then immediately take some damage and stop the trace logging. Your file should then contain only the code that gets invoked when the player's hit gets detected. Further playing with tracing / debugging can lead you to what decisions are triggering that code. It won't probably be a very big or complicated chunk of code, but may be more advanced in the sense of using pointers and indexed op-codes.

You can repeat this whole process for causing damage to enemies. You may likely find that both of those are quite similar and go from there hacking it. It is always possible that a clever hack may exist to just add a JSR into the enemy hit detection code.
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