Undo the Spire

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Author: Delfad0r

Last revision: 15 Nov, 2025 at 16:31 UTC

File size: 1.24 MB

On Steam Workshop

Description:

Undo the Spire is a Slay the Spire mod that adds a button to undo your actions in combat.

• Played a block card before you realised you had lethal? UNDO!
• Forgot you had Echo Form active and doubled a Strike instead of Biased Cognition? UNDO!
• Lost your Buffer to the Heart’s Beat of Death? UNDO!

With so many interactions happening in the game, it’s nearly impossible to be aware of everything at all times – unless you’re a certain Vietnamese player[www.twitch.tv], of course. Mistakes are inevitable, and it’s especially frustrating when a tiny misplay has the potential to ruin your entire run. If you’ve ever experienced this – and ended up resorting to savescumming accepting your fate and restarting, after your game decided to crash mid-fight – this mod is for you.

Undo the Spire literally only does one thing: add buttons to undo/redo your actions in combat.

• Allow undoing outside of combat (yet!).
• Work with controller (yet!).
• Guarantee that you boss swap into Pandora’s Box every time (yet!).

Undo the Spire relies on some fairly complex code to store all the information needed to undo and redo actions in combat. This code is specifically tailored to the base game, meaning that there is no guarantee that this mod will be compatible with other mods.
As a general rule of thumb, QoL mods that don’t affect the gameplay will usually work with Undo the Spire. These include:

• RelicStats;
• RNG Fix;
• Minty Spire;
• Mapmarks.

Content mods that heavily affect the gameplay by introducing entirely new mechanics (such as Downfall) will usually not work with Undo the Spire. There is a grey area in between, with mods that add cards/relics/characters but no new mechanics, which may or may not be compatible with Undo the Spire. If you are unsure, the easiest way to assess compatibility is simply to try: the undo/redo buttons will be disabled if incompatibility with another mod is detected.

1. Click the "Subscribe" button, just below the screenshot at the top of this page.
2. If prompted "Additional Required Items", click "Subscribe to all"; this will install other mods that Undo the Spire requires to function, namely ModTheSpire, BaseMod, StsLib, and Save State Mod.
3. Run Slay the Spire from Steam, and select "Play With Mods" when prompted. If you don’t see this prompt after you launch the game, open Slay the Spire‘s settings, and under General → Launch options → Selected Launch Option pick "Play With Mods" (or "Ask when starting game" if you want to decide on a per-launch basis).
4. You should now see a window with a list of mods. Select BaseMod, StSLib, STS Save State Mod, and Undo the Spire, together with any other mods you want to use.
5. Click "Play".

If everything is set up correctly, you should now be able to play Slay the Spire with Undo the Spire.

If you want more information, including how to report bugs, suggest features, contribute to the development of Undo the Spire, or you want to read a short essay on why an undo button can be beneficial for your Slay the Spire experience, read the README of this project on GitHub[github.com].
If you have anything to say about Undo the Spire and the comment section of Steam Workshop is too restrictive, feel free to hop in the Discord server[discord.gg]!
Finally, if you really enjoy this mod and want to go the extra mile, you can buy me a shop relic on Ko-fi[ko-fi.com]. It will make my day!