Hello :)
As for the Fishing, Farming, combat system (or any other mechanics), yes you can add as much as you want without any issue.
But as for the exploration (adding more worlds (Tiles)), then it depends on how big the world is, the more tiles you add the lower the performance might get, you can get thousands of tiles without any problem, but still if your worlds are huge, then you might start noticing performance issues, since the tiles are being taken into account when the player interact with them.
Though soon I will make a new extension (Culling) that can be used to make the template (or any game with a lot of world tiles) works with unlimited amount of tiles without affecting the performance at all :3
So yes, you can build anything on top of the template, but when it gets to adding more worlds (more tiles), you need to keep the performance in mind.
