Total cost and the steps involved depend on how much content you have but will usually involve me looking at existing game documentation, asking questions about code capability and playing the game.
Afterwards, you'll be provide a comprehensive, but easy to follow document explaining suggestions for new gameplay and how that it might be implemented.
This will usually take the form of new content, but I might suggest approaching existing content differently to add to the gameplay experience.
Want to see a finished example of how I altered existing gameplay to completely change how a game played?
*Service isn't intended for the entirety of new/adjusted content to be delivered, but some completed examples will be provided so that you or another designer can continue to add/adjust content in the same fashion.
*Want me to create or alter the gameplay for you? Check out the "Create or Change Gameplay" service!