Post
When runners phase through solid walls like ghosts, because collision detection is a polite suggestion, not a law.
Clipping exploits how game engines detect whether a player overlaps with solid geometry. Most collision systems check the player's position once per frame, and if you can move fast enough or position yourself precisely enough, you can slip between the cracks. Common clipping methods include building up excessive speed so the engine can't catch you between frames, using ledge grabs or crouch-stand animations that push your hitbox through geometry, or abusing corners where two collision surfaces meet imperfectly. Some clips require pixel-perfect positioning; others just need you to walk into the right corner at the right angle.
Example
In Dark Souls, players discovered that performing a backstep into certain walls at the right angle clips through them entirely. The 'Sen's Fortress skip' uses this to bypass one of the game's most punishing areas, saving minutes in any% runs by phasing through a wall that was supposed to be impassable.
Why it matters
Wall clipping is one of the most fundamental speedrun techniques across nearly every 3D game. It exposes the fact that game worlds are hollow shells held together by collision math, and any imperfection in that math is a potential speedrun shortcut.
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