How To Cheat

Maybe you accidentally reset your progress and want a quick way to get your content back. Or you're just curious. I'm not here to judge.

If you're not on Windows (or the Steam version of the game), some things will be different for you. You can still figure it out, probably.

Also, back up your files, or use a fresh profile. Unless you wanna risk messing up your save.

Navigate to:
C:\Program Files (x86)\Steam\userdata\"YOURUSERID"\2868840\remote\profileX\saves

Basically, go to your steam directory and open the userdata folder. If you only use one steam profile, there should only be one folder here. It looks like a long number.
Inside, there should be a bunch of folders whose names are long strings of numbers. These strings are unique IDs correlating to each game on Steam. Slay the Spire 2's id is 2868840. (You can find a Steam Game ID in the URL of it's store page.)
"profileX" refers to the profile you want to modify, ranging from 1 to 3.

Note: This is the local directory for your Steam cloud saves (sounds weird, I know). Slay the Spire 2 ALSO makes local saves to "username"\Appdata\Roaming\SlayTheSpire2\steam\"userid"\profileX\saves. However, at least for me, these are always overwritten by the files in the above directory, that's why we modify those.

If you're in the saves directory, and this profile has a current run:

Open current_run.save in a text editor (e.g. Notepad, VSCode). Inside, you'll find a lot(!) of parameters. Feel free to try anything, though some combinations WILL break your save.

Some things you can do:
1) Give yourself orb slots by changing "base_orb_slot_count": 3 to whatever number you desire.
2) Add/subtract health by modifying "current_hp": XX
3) Change your deck. You'll need the card ID for the card you want, which would be CARD.COMPILE_DRIVER" for Compile Driver, and so on.
4) Change your gold, energy, max hp, etc. Look for "gold": XX, "max_energy": X, "max_hp": XX.

And more.

My quickest method of "finishing" a run using the current_run.save is as follows:
0. Start a run, close the game, open current_run.save.
1. Give myself 99 energy.
2. Replace my deck with at least 2 of a powerful card that deals damage and draws (e.g. Compile Driver for Defect).
3. Switch normal encounters into boss combats (search-all: "type": "monster" and replace-all to "type": "boss" to do this for the current act.
4. Save the file, load the game, go right to one of the now omni-present boss encounters (recognizable by big, red "NOPE" placeholder art).
5. Kill the Boss using my infinite energy and infinite deck, proceeding to Act 2.
6. Save and quit, go back into the save file and run step 3. again (Act 2 is now generated in there).
7. Save file, load game, kill next Boss, etc.

Note: If you get a blackscreen instead of the main menu when loading the game, try deleting/moving your current_run.save file. It's likely breaking the game.

Note2: I suspect this works for Daily Runs (but haven't tried.) The highest highscores in the daily leaderboard are clearly not genuine, though I don't know by what method they are achieved. If you use the methods outlined to try and maximise your score, let me know how it goes!

Open progress.save in a text editor.

Lots of things to modify here. Lot of moving parts. Move too fast and you will almost certainly break something. You'll have to experiment a bit.

Concerning Ascensions: Changing your "max_multiplayer_ascension": and the per-character "max_ascension": works, IF Ascension (i.e. the relevant epoch) is unlocked on your profile. You also may have to give yourself some wins on the character, I'm not entirely sure.
You can unlock epochs if you have their IDs (derived from their name, same as cards, etc.), same for cards, potions, relics, etc.

That's it. If you have questions or need more detail, feel free to ask. I might not answer, though.

If this helps you, I'll be happy.