i didn't understand how to build :/
more instructions/tutorial is needed in the game :)
Viewing post in Core Defender jam comments
You have to click on the materials to spawn them and then you can drag them around.
You can only spawn materials if you have them which you have to buy with money (in the top left) by clicking on the plus icon to the left of the material
You start with 50 money and wood costs 5 stone costs 10 metal costs 20 arrow towers cost 20 and bomb towers cost 40