It's alright, however...
...potential downloaders, read the fine print: Zen mode is locked behind a paywall. The "free" variant of the game only contains the "endless runner" mode, with Zen mode being an in-app purchase. If you intend to download the game to use the game's Zen mode to relax and expect it to be free, then take note before you download. The devs have deleted my reviews that reveal this every time, and the game's description is quite deceptive—it makes it seem like zen mode is included as part of the base game, when it isn't. Even the App Store showcase makes it seem like Zen mode is part of the base game! If my review gets deleted yet again, then it'll only prove my point. While the game is good, such underhanded practices should not be supported—this kind of deception is likely to lead to something worse down the line for the game industry if kept unchecked and not called out.