Flow Free

Flow Free gives the player a grid with colored dots and a single task — connect dots of the same color with a continuous line so that lines never cross and the whole area is filled with no empty tile left. The controls are as simple as a touchscreen puzzle can get: place a finger on a dot and drag it to its matching counterpart, with the whole game played out in a single fluid gesture with no extra buttons or menus to distract you.

Big Duck Games released the title in 2012 into an already crowded logic-game market, yet Flow Free stood out thanks to the sheer purity of its idea — no bonuses, no side mechanics, just a growing grid size and, with it, a growing demand on spatial reasoning. It's exactly this asceticism that made it a popular tool even outside a gaming context, for example as a quick brain warm-up before bed or while waiting in line for anything. The free version with an unobtrusive ad also lowered the entry barrier enough that a wider range of players tried it than would have reached for a paid puzzle title.

The gradual addition of larger grids and "bridges," where lines can, after all, cross at one point, kept the difficulty moving even after dozens of hours of play. On a phone's small display, the game works better than on a computer, since a finger is a more natural tool for dragging lines across a surface than a mouse and click-driven cursor. The minimalist look — colored lines on a plain background with no unnecessary animations — also spares the battery and holds attention, so the game can be played even in the dark before bed without a distracting glare.

Why play it: Ideal for anyone who wants an easygoing yet mentally engaging puzzle with no unnecessary frills — quiet, a grid, and colored lines are enough on their own here.