The coordinate saga is complete and I guess the results were worth it. At least now I know it's not that difficult to expand the class hierarchy.
It's always great to plan stuff for the next year and then not get them done. But anyway, I hope in 2016 there will be more content and less engine coding. Level themes require a lot of work, but maybe it's less difficult than I think, because the vast number of existing techniques to create levels. It's more like combining those to create different kind of themes. Although I need a good labyrinth and town generator routines.
Next big task is the RPG system. Thinking of approaching it by creating interactions between game objects and the game world itself first, then object vs. object interactions. Exactly how to combine pseudo-physics to more traditional RPG rules is still a mystery. If it fails, it's always possible to degenerate to a traditional system.