You should certainly take a time to look at the state of the gender of main protagonists, since they are virtually always presuming towards male.
You have absolutely always male (most prevalent in FPS games eg. Doom, Halo, any Modern Military Shooter, Gears of War) I think out of the entire third person stealth genre there is not a single female(Thief, Deus Ex, Hitman, Splinter Cell, Metal Gear Solid, Ghost Recon, Assasins Creed, Dishonored): All absolutely male.
Then there's gender neutral games; Games that let you choose to be male or female, or don't presume either way. You'll see this most in Real Time Strategy games (since the protagonist isn't really shown) Like Simcity, Total War, Civ, Command and Conquer (although C&C Tib. Sun gives you playable GDI/Nod characters, both of which are male)
Simulators (flight simulator etc.) generally don't give the character a gender, but if they do it's male or heavily presumed to be male.
Puzzle/arcade style games are almost all gender neutral, but they don't really count since they don't have a protagonist.
Then there are the games where a choice is given: Again mostly RTSs, a few notable Role Playing Games KOTOR, Dragon Age, Mass Effect, Fallout, Pokemon, but there are some RPGs that don't give a choice, like Fable, Zelda, etc.
Finally the games that do have only female protagonists: Tomb Raider, Metroid, some of the Final Fantasy games... that's about it, I can't think of any more dedicated female protagonist games than in those 3 franchises.
You could do an entire chapter alone on Biowares' evolution of the female character in their games, going from KOTOR, which gives a male/female choice that is eluded to in later games that Revans' gender was unknown (although officially he's male and the main protagonist from KOTOR 2 is a female) to Mass Effect, which creates pretty much a split universe depending on whether you played as Shepherd or Femshep, right down to a reversible cover in Mass Effect 3 for people who rolled a female character.
You could even create a neat little chart organising a wide variety of popular games by their genre and male/female/neutral gender choice to see not just how many games actually have the ability to play as a female, but also which genres are the best/worst at giving the player choice.