Zen Bubbles

Intro
Zen Bubbles is a math puzzle whose rules are easy to learn but becomes challenging as you advance.  It's a chill, touchscreen-friendly puzzle that gets you to think deeply about numbers.

The math involved is similar to the classic math puzzle 24, but the feel of the game is closer to Flow Free.  

Goal
Each puzzle consists of a set of numbers, represented as labeled bubbles on the screen.  Dragging a bubble into another combines them using a mathematical operation (addition, division, or subtraction) that depends on the situation.  The goal of each puzzle is to combine all the bubbles to a single bubble with value 1.  

Rules
(If these rules look complicated, there is an interactive tutorial.)

1. ( + ) Dragging a larger bubble to a smaller implies addition.  The larger bubble absorbs the smaller bubble, increasing its value accordingly. 
2. ( / ) Dragging a smaller bubble to a larger attempts a division.   If the division would have no remainder, the combined bubble is the result of the division between the two values.  (If it cannot divide with no remainder, then the smaller bubble will stop, and they won't combine.)
3. ( / ) Combining two equal bubbles also performs a division, and the result is a bubble with value 1.  (You cannot add two equal bubbles, they always divide to 1.)
4. ( − ) Bubbles with value 1 are special.  They perform a subtraction by 1 instead of a division.  (Division by 1 occurs only for the case of two 1s combining, as above.)   

Thus, to end up with a 1,  your last two bubbles must be either two equal bubbles (for N/N = 1) or a 1 bubble and a 2 bubble (for 2 - 1 = 1).  

Gameplay
You can Undo your moves if you think you made a mistake; ask for Hint, which lets you know if the puzzle is solvable from where you currently are; or Give Up if you want to see a solution.  The solution is displayed as a mathematical expression.  

When you solve a puzzle, the next puzzle has a largest bubble that has a higher value than the puzzle you just solved, so the numbers involved gradually get larger.   (Each puzzle is randomly generated but checked to be solvable before being served up.)

There are eight different levels that you unlock by achieving enough points in the level below.  The levels vary in the number of bubbles per puzzle as well as the starting value of the largest bubble.  

You can play normal mode, which is chill and untimed, or there is also time trial, if you want to knock out a quick game or test your speed.  The number of minutes given for the time trial is the number of bubbles in the chosen level.  

The high score for each level and game mode is recorded.  

Available Versions
Currently only a Windows version is available.  Other versions will come soon.