write a to-do list of the things needed to finish it in a short time frame and then go do it and move on.1. stop using todo-lists.
usually todo-lists contain stuff that you dont like to do. stuff that you like to do you just do, no reminder required. having a list of things that suck will not motivate you.
better make a list of awesome things you like to have in your game and then code them (or learn first, then code).
other then that, i do not have an advice for you. really depends on what kind of person you are and the project ofc.