Alarm clock with soft vibrating mode? When staying in a hostel or going camping with a group of people, I need to use an alarm clock that can wake me up by vibrating instead of playing music.

Until now, I used CyanogenMod's internal app, which does support both modes, but its vibrating mode is too fast. I need something more gentle, and available on stock Android :-)

I checked Gentle Alarm, but it's just too complicated.

Thank you.
Timely has this option. When setting up an alarm, select silent for the audio part and then check the vibrate option. 

You can find Timely here. I have used Timely for years and I love it. XD

Edit. Had to fix the link. Sorry about that.