In this post I will explain the building mechanic in the game. Since this game is a more relaxed incremental game, the building mechanic is designed with simplicity in mind.
There are currently 4 things to build: grinders, railway, minecart and storage areas. The base is divided into columns and each column has predefined spots for the different things to build.
To build something new you only need to press the corresponding button in the upgrade/build menu at the left of the screen to build something. There are some controls that decide where it is built and how many are built.
Where it is built depends on what is selected. When building new rail or adding more minecarts it will be added to the columns that are currently selected. If nothing is selected, rails or minecarts will be built on all columns that already have some rail built for them as long as you can afford it.
New grinders are added to the left or to the right edge of the base depending on if you press the add left or the add right button. New storage areas are added below all grinders at once.
So let’s get to the question in the title, is there a limit to the size of the base? Yes, there is actually a limit, as there often is. However it is quite large. Currently the map of the game is 32k columns wide, which means the base can be maximum 32k columns wide as well.
In depth the actual theoretical limit is about 2 billion so that is how deep you can build the railway of the base. As of now there are no interesting changes in the gems after about 4k in depth, so that is the current planned practical limit of the game, but there won’t be anything stopping you from mining further except for time. I’ll know after all the upgrades are done how far it will be practical to mine.