I am an indie game developer currently working with corona sdk and lua programming language. Based on your concept I plan to split the project into 3 milestones the first is completing a basic skeleton of your game(no effects, or sprites or animation or such), the second milestone will be fleshing out the game adding animations, sprites extra features and the final milestone will be testing and debugging to ensure you have a proper fun game created. Please note that depending on how complicated your concept is a few extra days of development time may be necessary for a polished game. Please contact me if you to discuss further details.