NPC collision bypassing glitch
The NPC collision bypassing glitches describe glitches in Pokémon Red and Blue in which an NPC walks through another NPC or object.
This glitch was documented by Roelof and recorded by ChickasaurusGL, in which an NPC would walk through through the Cable Club lady.
Analysis
According to Bbbbbbbbba from the forums, the glitch can be recreated if one of the following criteria is met:
1. The game is saved at "exactly at the frame when the walking NPC was ready to move, but hadn't decided in which direction yet.", and then the game is saved and reset.
2. If the Start menu is opened, at the same time as 1., and that this action obscures the sprite.
It is possible to recreate the glitch on an emulator by observing the correct memory address at wSpriteStateData2 (represented by $C2x8) for the given NPC[clarification needed]. This address controls when a walking NPC is going to make their next step. If $C2x8 is 0x01, opening the Start menu will change this value to 0x00. From there, saving the game or obscuring the sprite with the Start menu and closing the Start menu, may replicate the glitch.
Youtube video
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