In order to complete a game developers usually focus on the concept of production. It consist of four different procedures starting with developing a concept. It can be a simple idea such as a warrior trying to take back his island from another king. After the concept is created they follow it up by pre production. This is essential as pre production focuses on the story, licence, level design, winning outcomes, mechanics and have an overall  blueprint.  Production follows up next and this is when the artist create their magic using 3d programs and code gurus work on game functions and a.i.  Lastly the team does post production which consist of testing the game for minor bugs so programmers can edit out. Games usually have betas for players to play which is actually a test for the developers and programmers see if everything is running ok. One you have a team which doesn't consist of one or two people developers should usually create a project management tool. This tool will have team members do specific task required to finish the project in an  organized manor. You must have a team-oriented approach when dealing with PM tools.