Taking a zero player game and adding more

It's game jam time again and this time I'm going to try to finish one for submission, I have brainstormed this one over the last couple of days and I think I have come up with something that fits with the jam's theme, I have started to create the classes needed for the core machinic and built a TTD framework for the game classes. Unity is very complicated when it come to Unit testing so I am just focusing on the minimal required classes for the game to work and I plan to slap together an extension framework to make the 'zero player' game  into a multiplayer one.