Some games use a mechanism to reflect which side has the initiative. As to what initiative is, the online OED offers "the power or opportunity to act or take charge before others do" which fits pretty well with games that empower one player or the other to move first, or decide who moves first.
It can be a fun and exciting mechanism. Random or semi-random initiative shifts can reward risk-taking on one hand, and encourage caution on the other just by removing certainty from the sequence of play.
However, I do have a couple of concerns with random initiative. One comes from a criticism quoted by Frank Chadwick in the design notes for Volley and Bayonet which deprecates "rags-to-riches" die rolls, that concentrate incredibly important consequences into a small number of random events.
Another is a comment by Mao in On Guerrilla Warfare : No military leader is endowed by heaven with an ability to seize the initiative.
So, if we don't want dice representing the mandate of heaven, what do we want to do about initiative? The simplest approach, I think, is simply to provide players with a predictable turn framework that empowers each to struggle for and gain the initiative, without having an explicit "initiative" rule.
We will consider the implications of this in a later post.
At the moment, I am going to watch a bit of TV while the hard disk defrags. If you have been following this blog, my apologies for the paucity of posts over the holidays, but there will plenty of time for more design as the dull weeks of February approach.