It was only possible on a select few maps, most notably those made by goldbond, since he had a habit of putting his maps below the z-axis. It was caused by roundoff errors in the player movement. The more movement packets you sent, the more roundoff error there was. Values round toward 0, so if you're below 0, it rounds up, making you jump higher. If you're above 0, it rounds down, making you jump lower. I fixed it because it encouraged people to waste bandwidth, mostly. It also made it unfair for people who didn't have both a fast computer and a high-speed connection. It only affected 2 or 3 maps, anyway.
