I just make a very simple game Tap Again.
It's designed as simple as possible.
It plays with reaction time only.
I think it's addictive.
I can get over 100 in it, what about you?
Would you like to try it?
How to play : tap following the pace of square appearing&disappearing.
Here's the link to install:
https://play.google.com/store/apps/details?id=com.tapagainfree