That's just the simple sequential sense of "first," the first that comes before second, third and fourth; but there's something more radical here than the ordinal or sequential sense of "first."

这只是“先“表示顺序的简单含义,先于第二，第三，第四的那个“先“，但这里,“先“除了表示顺序的意思外还有更激进的含义“

耶鲁公开课 - 弥尔顿课程节选

But in the real world that's a sequential game, people decide to run in some order, we're going to assume this is all simultaneous.

但在现实生活中这是个有顺序的博弈,人们依照某种顺序决定是否参选,我们将假设这全是同时发生的

耶鲁公开课 - 博弈论课程节选