Quasimorph save compatibility depends on the exact branch and version, not only the title shown in your Steam library. The official 1.0 launch notice says saves from the default branch were not compatible with 1.0, while saves from Unstable Beta were compatible. Use that warning as a reason to identify your state before updating, not as permission to delete or overwrite anything.
Identify the product
Check that Steam is launching Quasimorph AppID 2059170, the base game covered by this guide. End of Dream and the Supporter Pack are related products with different scopes. A save or mod instruction for a different AppID must not be assumed compatible just because the product name begins with Quasimorph.
Then note the public release state. The base game left Early Access at 1.0 on 2026-07-31, and the official news feed records hotfixes and 1.0.1 afterward. Write the date you made the backup and the version visible in the current client. If you are troubleshooting, include whether the problem started immediately after an update or after a branch change.
Understand the 1.0 warning
The launch announcement gives one concrete compatibility rule: default-branch saves from before the 1.0 transition were not compatible with 1.0, while Unstable Beta saves were compatible. It does not say that every later update will behave the same way. Treat compatibility as a version pair: old branch/version to new branch/version.
If the game offers a migration, read the warning and preserve the old copy first. If it fails to load, capture the message, branch, AppID, and whether mods were enabled. Do not repeatedly launch a questionable save while Steam Cloud is active if each launch could upload a changed state. Investigate with a duplicate or a documented backup whenever the platform allows it.
Back up before changing branch
Before switching, close the game normally and identify which save location the current installation uses. Make a dated copy outside the active save location, then record the current Steam Cloud status. The exact filesystem path can differ by environment and should be verified locally; do not copy a path from a different platform without checking.
Disable or remove one mod at a time only when the issue is plausibly mod-related. A save created with a map pack, content mod, or configuration change may depend on that content. The Workshop and in-game manager make activation easier, but they do not prove that an older save is safe to open without its dependencies.
Recover methodically
Use a small test sequence. First launch the exact old branch with the backup untouched. Next test the target branch with a copy if the game documentation allows it. If the copy loads, inspect several systems: ship, crew, inventory, mission panel, and current settings. A save that reaches the menu but loses items or a mission state is not fully verified.
If the problem persists, stop changing settings randomly. Record the error, public version, branch, operating system, active mods, Cloud state, and the last successful launch. That information is more useful for a developer report than a claim that “the save broke after an update.”
Safe to test
A dated backup exists, the AppID is confirmed, and the old branch/version are written down.
Pause
Steam Cloud is asking to overwrite, the branch is unknown, or the save depends on a removed mod.
Report
Include exact versions, branch, platform, mods, error text, and the last known-good state.
Use current news as the boundary
The 1.0.1 patch focused on interface explanations, mission difficulty, trading information, active implants, and mission preparation. These changes can alter what a returning player sees without invalidating every concept in an older guide. Compare the current UI first, then update the smallest part of the route that no longer matches.
For the broader systems context, read Systems. For a returning-player summary of released changes, open Updates. A backup and a clear version note are always more valuable than an unverified promise of compatibility.