If you have your art assets, know basic programming, are familiar with construct2, and have good work ethic you could easily complete this much quicker than that. I give the basic logic framework a difficulty of 4. I give the data management, to include persistent data management and offline earning calculations and handling a difficulty of 6. However, unless your making a straight up clone, I give gameplay balance (ie. making it engaging and fun) a difficulty of 10.
A quote comes to mind though... " "Level's Jerry, I'm building levels."