Please download this archive:
Once downloaded extract it's content, the C3.inf and C3Map.inf files, to the root of game's installation folder, overwriting existing ones.
In order to navigate to game's installation folder:
- If the game was installed via GOG GALAXY, please select the game in GOG GALAXY, click on More -> Manage Installation -> Show Folder
- If the game was installed via offline installer, then you will have to manually navigate to the game installation folder, by default it's: C:\GOG Games\Caesar 3\
Windows 8 and 10 users: Please right-click on the game's shortcut, select Properties. Switch to the Compatibility tab, and enable Reduced color mode and set it to 16bit.
Windows 7 and older versions users: Right click on the Desktop, select Screen Resolution. In Screen Resolution window select Advanced Settings, here switch to Monitor tab, and change Colors to High Color (16Bit).
Once reduced color mode is set, start the game. It should boot up in windowed mode that you can resize freely.