源于把up当动词“提升”用的日本英语。
The term comes from Japanese katakana-English. \"~ UP\" (Japanese: ～アップ) means \"to raise the ability of, to increase.\" Some English study books in Japan have phrases like \"Ability UP!\" written on their covers. This Japanese shortening of English has provided us with another popular gaming phrase, level up; though Dungeons and Dragons aficionados may disagree about the origins of this oft-invoked phrase.
http://en.wikipedia.org/wiki/1up>1UP=one user player
>我以前看到的解释是省略标记，up是前缀，应该是1 up(date/grade)之类……
这两个解释都是后来的人从英语使用者的角度推测产生的结果...但在日本，英语不是那么用的~
同理，马里奥最早的名字，有的资料说叫作Jumpman，有的说叫作Mr. Videogame（在db的文章中两者都出现过^^;;），显然前者是对的。