My Casio Protrek PRG-70YT has 3 diagnostic modes:
- Tilt sensor/trigger
- Power Saving/Solar Charging
- LCD test patterns and movement number display
With 20 years of use, still on the first battery and it is super accurate (couple of seconds per year), they don't make the like they used to.
I'm a fan of older Casio watch releases. I have 1/2 of dozen that still work fine!
What is not to like:
- solar powered and never needs a battery
- 'radio controlled', self calibrates time every night
The ONLY 'not so fun' part is trying to remember how to change daylight saving time 2x a year.