Presented by Displaced Gamers, "The Complex Code of Mega Man 2" breaks down the crazy medley that is Mega Man 2's code. It's a pretty insightful piece that, among other things, shines a light on the game's ever-so-critical "ejection" logic, which is necessary to perform the famous zipping bug.
Zipping is a strategy used by speedrunners to skip past whole portions of a stage. Why does it work so satisfyingly well in Mega Man 2? Well, it turns out Mega Man's left-facing ejection logic is OFF by one pixel. If not for that single pixel - an oversight from the game's three month development period - decades worth of Mega Man 2 speedruns would be a very different.
Source: Displaced Gamers