Adding Content

From here, what exactly to do depends entirely on what you want to make.

If you plan on making a character, start from Adding a Character and then move on to Adding Cards and Adding Relics.

If you want to just add content to existing characters, just go straight to Adding Cards and Adding Relics.

For anything else, you'll likely need two things: other guides, and looking at examples.

For most things you'll make, there will be something similar in the base game you can learn from. You can view this using IntelliJ's built-in decompiler, Fernflower, or an external decompiler like jd-gui.

For in-IntelliJ decompiling, double-tap shift and click the check box to enable Include non-project items. You can tap shift 4 times to accomplish the same thing. Then just search for whatever you want to look at and open it.

For references, the most useful will likely be the BaseMod, ModTheSpire, StSLib, and libGDX wikis.

The BaseMod wiki explains how to add various types of content using the hooks it provides, along with other features that you may find helpful for the content you're trying to create. I would recommend this one first.

The ModTheSpire wiki explains patching, which will be necessary for more complicated mods, such as if you want to add your own mechanics.

StSLib provides some commonly-used features, mainly for cards and relics.

libGDX is the framework used by Slay the Spire. This wiki can help you understand how the game works, along with having useful lower-level information.

Rather than attempting to link to every tutorial ever made, I'll recommend you go to the Slay the Spire discord and ask around in the #modding-technical channel if you know what you want to make but can't find the information you need.