halo & games

One of my most favorite games is Halo. it's quite a fun game and I am a type of person who likes to play shooting games. I am also working on a game called Erox X it's sorta like runescape a online game were you go and kill guys and do things, you can become a mage, swords man, archer, or tamer. Then you choose a side good or evil, or just stay the same. You as a tamer can go and find dragons horses ... and tame them, after that you can sell them or ride them to go faster or as a normal person just run. Another nice thing about the game is if you are a mage you can turn into a swords man vise versa. in this game you can talk to other people. But there is only one problem...... I need a program to design it so right now its just a bunch of paper and sketches.