Updated 2026-09-05

Steam Cloud and your Isaac save: replacing a file without losing it

Steam syncs the Isaac save folder before and after every session. Replace a file without telling Steam about it and the old version comes back, or you get a Cloud Conflict window with a wrong default. Here is what actually happens and the procedure Nicalis itself recommends.

How the sync works

• Steam synchronizes the game’s cloud files before the game starts and after it closes (Steamworks documentation).
• If the local files differ from the cloud copy and Steam cannot tell which is right, it shows a conflict window at launch. You must pick a side; the other side is overwritten.
• Which folder the game reads is decided by SteamCloud in options.ini, not by the checkbox in Steam. See the save file location guide.
• Playing in Steam Offline Mode almost guarantees a conflict later, according to Steam Support.

The official procedure (Nicalis)

Nicalis published these steps in January 2024 for restoring a backup during the online beta. They work for any replacement file, including one exported from this editor.

1. Make a copy of your current save files somewhere safe.
2. In the Steam library right-click The Binding of Isaac: Rebirth, open Properties, and on the General tab switch Steam Cloud off.
3. Open the folder where the active saves are kept and copy the new file there. Name it after the slot it should replace: persistentgamedata1.dat in Documents, or rep+persistentgamedata1.dat in userdata\…\250900\remote.
4. Launch the game and check the slot on the save select screen; completion marks show on the character select screen.
5. Close the game, open Properties again and switch Steam Cloud back on.
6. Launch the game again. Steam reports that the cloud and local files differ. Choose the local files and they overwrite the cloud.

The Cloud Conflict window

The current Steam client titles it “Cloud Conflict” and offers two buttons, Local Save and Cloud Save, each marked Newer or Older with a modification date. To keep the file you just installed, choose Local Save; the cloud copy is then overwritten with it. Choosing Cloud Save throws your edit away. A separate “Unable to Sync” warning has a “Play anyway” button; Steam Support says playing through it can lose progress.

The alternative: SteamCloud=0

Instead of toggling the checkbox every time, set SteamCloud=0 in %USERPROFILE%\Documents\My Games\Binding of Isaac Repentance+\options.ini with the game closed. The game then reads and writes persistentgamedataN.dat in that Documents folder and the cloud stops interfering. Zamiell’s FAQ recommends this setup because it keeps every file in one place. Search the file for the key name rather than a line number; patch 1.9.7.16 added EosCrossplay and the layout changes between versions.

Two things to keep in mind. First, the game rewrites options.ini from its menus, so edit it only while the game is closed. Second, switching the key moves the game to a different file: the Documents copy may be older or empty. Copy the save you want into Documents before you flip the switch.

When the old save keeps coming back

Forum reports describe the game restoring an older Repentance+ save even with the cloud disabled. Two fixes are used in practice:

• Empty save_backups (move the files elsewhere) before placing the new file, then launch. Several guides list this as a required step.
• Delete the cloud files whose names start with rep+ (and rgon if REPENTOGON was used) with a third-party Steam Cloud File Manager, then launch. Steam does not support this; back everything up first.

You can inspect what Steam holds for the game at store.steampowered.com/account/remotestorage, and the sync log is Steam\logs\cloud_log.txt. Steam Support does not recover lost saves and does not resolve conflicts for you.