So first of all, you need to think through your idea. Rate the games market, which is now represented. Do not examine it with the goal of cloning existing projects, make a list of pros and cons of each game, including a brief description of focus, fantasy, economic, military or post-apocalyptic. The more games you will be able to see, the better you will be aware what exactly is lacking in the market right now.
Once you have finished the idea, write an example scenario of the balance of forces. Most successful projects use a mechanism of gameplay, as an RPG – in this case, each player independently develops your character in the game world, completing tasks and collecting rewards in the form of experience and game currency.
The number of parties that can be played by a user, shall not exceed four, otherwise it can be confusing. The choice of the parties will depend on the way of character development. If the game world is "everyone for himself", the players should be able to unite in clans and alliances. Be sure to use the rating system of players – this will foster their competitive spirit.
Hire a team of developers and invite third parties to test the product. In case you are not very good with narrative, you can grant the right to write the script for the game the other person, of course, for a fee.
Remember that the game must make a profit – enter the special game items that can be bought for real money and use exchange real money for game. Monitor the development of the game, make changes if necessary, and constantly bring something new to the players do not have time to get used to.