@Yuuki Paint Sai and a tablet.
For this game, unless you are going for the comedic/parody route, I would want a really, really good reason for females and males to fight each other. For that matter I would want a very good reason as why the females are still able to fight. A human population usually sits around 50% for males and female because of the chance of a child being male or female. Unless all the females are Amazons or have some advantage, such as technology, they wouldn't be able to hold against males. Males have the advantage on strength, physique and psyche. Though if you can write it well, it could be very interesting, I would just want pretty good rationales, unless it isn't meant to be serious.
A good example of females and males at war in a really serious sense would be the Black Jewel Series (series of books, not for young ones though) The overview of it is
One strong and ambitious female wanted power. She gathered like minded people and destroyed the stronger opponents and potential threats. She twisted the weaker males and chained the stronger ones when they were young. The males, fearful of females reaching powerful maturity, destroyed them while young. Females, fearing the males, chained powerful young males. Thus a dangerous spiral was created were the strong destroyed potential threats. This is set in a world were females are the stronger sex and are meant to rule, and males are to serve and protect. The spiral is a corruption of what they are and why the war between the sexes will eventually destroy them all.
This is a rather dark example, but it is rationally built up and both sides have a reason for doing what they do. Females and males wouldn't fight each other without good reason. Plus, it has a pretty good stance as to how females stand against males you are physically stronger.