Infinite Zen is the mode without a deadline. There is no timer, no daily reset to race and no shared cube to compare against — just a run of randomly configured cubes that continues as long as you keep winning. It is the mode to reach for when you want to practise deliberately, or when you want the puzzle without the stakes of a daily.
Each cube in a Zen run is generated fresh with a random configuration: the grid is anywhere from 5×5 to 10×10 per face and the palette from 5 to 10 colours. That is 36 possible combinations, and Par comes from the same difficulty table the rest of the game uses — from 16 moves on the smallest, simplest cube (5×5, 5 colours) up to 61 on the largest and busiest (10×10, 10 colours). Zen cubes are clean: no blockers and no powerups, unlike Challenge and Power.
Because each cube is rolled independently, difficulty does not ramp. A 10×10 with 10 colours can follow a 5×5 with 5 colours. The run is a sequence of unrelated problems rather than an escalating ladder — that is what makes it useful for practice and unsuitable as a difficulty test.
You get one life: lose a cube by running out of moves and the run is over, with your totals recorded. While a run is alive the game tracks how many cubes you have completed, your total moves and your total time, and the run is saved as you play — you can leave mid-cube and pick the same board back up later the same day.
Access: Infinite Zen needs a free account, because the run persists server-side between sessions. It is open at weekends; on other days you can unlock a run by watching an optional ad. Nothing about the mode is for sale.
The random configuration is the feature here. Different cube shapes stress different skills, so you can wait for the shape you want to drill and use it on purpose:
A drill that transfers well to the dailies: on each move, name the colour you expect to take next before you commit to this one. Zen is the cheapest place to practise looking two moves ahead, because losing a Zen cube costs nothing but the run.
Zen cubes are not on the leaderboard — the leaderboard compares players on identical daily cubes, and Zen cubes are unique to your run. Zen also does not feed the daily streak. It is practice and it is a way to unwind; the competitive surface lives in Daily Double and Challenge Cube.
Start a run, or read the Strategy Guide first so the practice has something to aim at.