Hi there! I see that your Blockudoku app on your Mac keeps crashing right at the developer screen and hasn’t loaded properly for about 36 hours. That sounds like quite the hiccup. To help you better, can you tell me if you’ve tried restarting your Mac or updating the app recently?

In the meantime, here’s a step-by-step approach that often resolves issues like this on macOS 10.15.7:

1. Restart Your Mac
Sometimes, a simple reboot clears temporary glitches that cause apps to crash.

2. Update the App
Make sure your Blockudoku app is updated to the latest version available on the Mac App Store. Developers often release fixes for crashes.

3. Clear App Cache and Preferences
- Quit the Blockudoku app if it’s running.
- Open Finder, then press Shift + Command + G and type ~/Library/Containers/ and look for any folders related to Blockudoku (could be named after the developer or app).
- You can also check ~/Library/Application Support/ for Blockudoku folders.
- Move those folders to the Trash (this resets app preferences and cache). This step won't delete your purchase but may reset some settings.

4. Reinstall the App
If clearing cache doesn’t help, uninstall the app completely by dragging it to the Trash and then reinstall it from the Mac App Store.

5. Check System Updates
Although your OS X 10.15.7 is fairly recent, double-check there are no pending system updates that might improve app compatibility.

If after these steps the app still crashes at the developer screen, there might be an issue with the app version compatibility on macOS Catalina or a deeper bug that needs developer attention.

Would you like me to help you with clearing the app cache or reinstalling, or would you prefer some instructions on checking system updates? Also, please let me know if you see any error messages when it crashes.

Are you satisfied with this initial guidance? We can dig deeper if needed!