Note: Talk: Explaining the MissingNo glitch in the Game Boy Pokemon games
Siân Griffin gives a very approachable breakdown of the collection of bugs and compromises that lead to the famous MissingNo glitch in the classic Pokemon games.
This talk gives a great introduction to how Game Boy games were authored (assembly!) and the clever optimizations that went into writing games within these constraints. You’re left with profound respect for the authors of these games, and the way these constraints required the authors to have immense technical creativity.