HeyUtho
An Android alarm you can only turn off by doing math
HeyUtho is an alarm clock with no snooze button. When it rings, you have to solve three quick math problems in a row before it goes quiet, and one wrong answer sends you back to the start. By the time you've done the math, you're awake. It's free and open source, with no ads and no account, and everything stays on your phone. The name is Bengali: "utho" means "wake up".