We are aware of an issue with the launch resolution of PC Building Simulator that can lead to the window launching at a very small, unplayable size.
If you play on PC, try the following steps:
Uninstall the game and carefully use regedit.exe to remove the "PC Building Simulator" registry key "Computer\HKEY_CURRENT_USER\SOFTWARE\The Irregular Corp\PC Building Simulator"
Reinstall the game.