ONO: Brain Fog app for iPhone and iPad

Fun! Fast! Free! Unique! Think straight.
Start a chain reaction that will clear all the Os from the screen -> ONO (no Os).
A new type of puzzle game. Like Sudoku without numbers. Wordle without letters.
Starting with the simplest forms + rules, complexity and variety emerge as elements are added.
A fun easy way to work on your clarity, focus and working memory.

24 levels from very easy to very hard. Master each level by solving 4 puzzles - you are allowed three tries in each of the first two, two tries in the next and, finally, you must solve one puzzle in a single try. The level is then open for free play with three tries forever. Ads only required for bonus rewards: You have an opportunity to watch a :30 ad to unlock a level and/or to get 2X points to help you run up your score. 
Unlock everything for just 99¢! Larger levels have 1000s of puzzle variations making ONO a game you can play over & over.
*Hat tip to "A Thousand Brains" by Jeff Hawkins, you should buy this book.