The Waterpark Simulator Demo is a separate Steam product, AppID 3730180. The full game is AppID 3293260. CayPlay updated the Demo on July 31, 2026 and published an unusually specific save boundary: saves made in the updated Demo can be opened in the full game, but a save opened in the full game cannot later be reopened in the Demo.
There is a second boundary that matters just as much. Old Demo saves are incompatible with the updated Demo. Do not combine these rules into the inaccurate promise that every Demo park transfers. The supported direction begins with a save created by the new Demo build.
Identify which Steam product you are running
Open the Steam library entry and check the title before changing a park. The Demo and full game have different AppIDs even though their names are closely related. A desktop shortcut or recent-game entry can make the distinction easy to miss.
If you are troubleshooting files, keep the product identity in your notes. Say “Demo 3730180” or “base game 3293260” rather than only “Waterpark Simulator.” The products can have different executable state, content boundary, and save behavior.
The soundtrack, AppID 4811280, is a music product and has no gameplay-save role. The older same-name game with AppID 1362910 is unrelated and must not be used for file or migration guidance.
Understand the supported transfer direction
The official Demo notice establishes this sequence:
- Create or continue a save in the Demo build updated on July 31, 2026.
- Install and start the full Waterpark Simulator game.
- Open that compatible Demo save in the full game.
- Continue it as a full-game save.
Step four is a one-way transition. Once the full game has opened or advanced that park, do not expect the Demo to accept it again. The full game can contain systems or data that the Demo does not understand.
Before the first full-game open, make a manual backup using the backup-first process on the save recovery page. Preserve the untouched Demo-era copy separately. A backup is not a method for forcing an incompatible save into an older product; it gives you a recovery point if you selected the wrong file or changed your mind.
Separate old and updated Demo saves
The July 31 notice says old Demo saves are incompatible with the new Demo. If a park was created before that update, do not present it as eligible merely because it belongs to AppID 3730180. The relevant question is which Demo build wrote the save.
Keep older files intact while testing. Do not rename a backup to imitate a new save, edit its contents, or repeatedly open it in different versions. Those actions can destroy the evidence needed for support.
If the updated Demo does not list an older park, that result is consistent with the published boundary. Start a new Demo park or use the full game according to the options Steam and CayPlay currently provide. The official notice does not promise a conversion tool for pre-update Demo data.
Prepare a clean handoff
Update both products through Steam before testing. Close the game completely, allow Steam Cloud activity to settle, and copy the relevant local save directory before launching the destination product. Label the copy with product, date, and state, such as demo-3730180-before-full-open.
Start the full game and inspect its save-selection interface. Choose only the intended Demo park. After loading, check the park name, map, money state, attractions, and recent progress before saving over anything. If details are missing or the park is clearly wrong, exit without making more changes and restore from the untouched copy.
The exact file-selection interface was not captured in the audit, so this page does not invent a button path. Follow the current public-build labels and take screenshots if they differ from the official notice.
Know what transfer does not prove
Opening a Demo save in the base game proves neither feature parity nor backward compatibility. The full game can expose multiplayer, progression, maps, achievements, or construction features absent from the Demo. A transferred park also does not establish that every full-game achievement will retroactively unlock.
Steam Cloud support on the full game is not evidence of console cross-save. The official metadata covers Steam Cloud for AppID 3293260; it does not promise movement between unrelated platforms or accounts.
Do not test the one-way rule with your only copy. Once the full game writes later-format data, trying to load that file in the Demo contradicts the published boundary and can create unnecessary risk.
Escalate a failed eligible transfer
If a save was definitely created in the updated Demo and the current full game cannot open it, preserve the original file and gather a short report. Include both AppIDs, the date the Demo save was created, when each product last updated, whether Steam Cloud was active, and what the full game displayed.
Use the official destinations on the official links page and provide CayPlay with the smallest reproducible sequence. Do not upload private account data publicly. A clear product-and-version report gives support a much better starting point than “my save is gone.”