Added a resource to allow upgrades to towers.
For those who haven’t used Godot, a resource is a fancy name for a data container that counts the number of other objects referencing it and automatically frees itself when it is no longer needed. According to a quick glance at the Godot docs, creating a custom Resource is as simple as creating a new script that extends Resource and adding a couple of @export variables.

I failed at step one, used the default ‘extend Node’ instead of ‘extend Resource’, and then spent over half an hour trying to work out why it didn’t show up in the inspector.

Lesson learned then?

Not really, because I did the exact same thing again the next day.