I made this because I don't want to look into clocks when I am waiting for a train.
I will be trying default files more and I will change them often, maybe.

Usage:
Push "Start", then the alarm vibration runs independently of app, even after app finishes or the screen goes black. (Old devices may not move well in doze mode.) Please push "Stop" button or the notification to stop when you want to stop vibrations.
(Even if you deny the permission for Notification, yet the vibrations occur. In this case, please boot the app and push "Stop".)

The alarm keeps the vibration pattern at the time "Start" was pushed. The pattern is not changed when you change the setting just on the app. The pattern is changed only when you push "Start" again.
The alarm time is displayed on Quick Setting Tiles or Clock widget when the alarm runs. But the alarm time also appears when other alarm apps run at a same time, so you can not distinguish which app runs. Please push "Start" or "Stop" if you don't know which app runs.
The alarm vibrates 1 or 2 seconds after the exact minute (00 second). It is on purpose.

You can change settings by swiping right, delete by swiping left, and add by pushing "+". The minute already existing in settings is overwritten.
In the page for changing and adding, you can try vibration patterns repeating at intervals of 10 seconds. Please try the repeating and put your phone into your pocket.
I feel that 0.1 second of vibration on my hand is very strong and loud, but 0.5 second of vibration in my pocket is very weak. My left knee feels Vibrations of my phone on the right edge of a cheap table in McDonald.
"Strength" can be controlled in some phones. But I don't have any phone able to control, so I don't know how different.
When you push "+" to add setting, app searches a minute which is not set, in order of multiples of 10, multiples of 5, and others.
You can change the setting in the block by conditions. Some condition may be difficult, but you can change faster than individually, maybe.

You can save settings as file. 12 files are prepared as default files and you can overwrite these files. If you delete default files, app remakes these when the next boot.
You can read or write files in External Storage. If you use Text Editor which can rewrite android/data/.../files, you can edit them.