Hi there! I see you mentioned "Not working" and then asked about a 'Color Block app troubleshooting guide.' Could you tell me a bit more about what exactly isn’t working with the app? For example, is the app crashing, not opening, freezing, or something else on your iPhone running iOS 18.6? Knowing this will help me guide you better with the right troubleshooting steps.

Not opening

Thanks for letting me know the Color Block app is not opening on your iPhone running iOS 18.6. Let's try a few steps to get it working again:

1. Force Quit the App: Sometimes the app may be stuck on startup. To force quit, swipe up from the bottom of the screen and hold to open the app switcher. Find Color Block and swipe it up to close. Then try reopening the app.

2. Restart Your iPhone: A quick restart can refresh your system and clear temporary glitches. Hold the side button and volume button until the power off slider appears. Slide to power off, wait a few seconds, then hold the side button to turn it back on.

3. Check for Updates: Open the App Store, tap your profile icon, and scroll to see if Color Block has an available update. Installing the latest version can fix bugs causing the app not to open.

4. Reinstall the App: If the app still won't open, delete it by pressing and holding the app icon, then selecting 'Delete App'. Reinstall it fresh from the App Store afterward. Note that this may cause loss of saved game data if not backed up.

If after these you still cannot open Color Block, let me know, and we can explore deeper troubleshooting like checking account/login issues or device compatibility layers.

Does this help you get started? Are you able to try these steps now?