One of the first video games I recall playing, which featured a prominent female, was a game called Betty Bad. This game was one of many pre-installed games that came with my old HP home family computer. Although these games were merely free demos for the real game (which would have cost real money), I played them a lot. What stuck out about this title was that the hulking testosterone ridden body builder archetype we have become all too familiar with, was replaced with a chick.
As regrettably hesitant as I was at the time to play a female character, the game was actually very fun. I feel that many young men, particularly, are too prone to play male characters as opposed to female characters. Despite Betty's perfect voluptuous body, she's an undeniably bad ass character to play.
Although a female character was used in this game as a main character, the obvious reason is to give these young men something to ogle. The way she is portrayed in the game leans heavily on the "sexy" side. It's sad to see that women must be portrayed this way in order to gain attention from the male demographic.
images:
http://image.gamespotcdn.net/gamespot/images/2002/pc/act/bettybad/bettybad_790screen002.jpg
http://image.gamespotcdn.net/gamespot/images/2002/pc/act/bettybad/bettybad_screen004.jpg