This is likely a problem with the download package. Check your install folder in the "Summer Daze_Data" subfolder. Does it contain a file called "SteamSettings.ini" or a similar name? If so, delete that file and try running the game. It should not be in the itch.io build.
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Another user (on GOG) ran into a similar problem. A contributor on the Transolar Games Discord server found that it's likely caused by a system locale/region mismatch. Are you in a country that uses comma (0,25) to indicate a decimal number? The U.S. uses a period (0.25), and that can break the code. Our contributor suggested using Lutris to change the locale:
- Open Lutris
- Right-click on Summer Daze: Tilly's Tale
- Select Configure
- Go to the System options tab
- Scroll down to the Environment variables section
- Click the Add button:
- Key: LC_ALL
- Value: C
- Click Save
- Relaunch the game.
The "C" option causes the system to use standard English/Computer formatting for numbers.
Also please note that we have recently uploaded updated versions of Summer Daze: Tilly's Tale for all systems. This might fix your issue without having to change locale settings.