Playing on a Phone

Two layouts, two control schemes, and the specific problems that had to be solved to make touch work properly.

Touch versions of this genre are often bad. Making one good requires solving several specific problems, and it is worth setting out what they are.

The tap problem

The obvious approach is to reuse the keyboard's auto-shift timings for on-screen buttons. That fails badly, because keyboard auto-shift starts repeating after about 125 milliseconds and a finger tap comfortably lasts longer than that.

The result is that every tap moves the piece two cells. Precise positioning becomes impossible and the game feels broken.

The fix is separate timings for touch: a longer delay before repeating and a slower repeat rate, so a tap is exactly one cell and holding still slides.

The flick problem

Flick down to slam, drag down to soft drop. These are the same gesture in different amounts, so the game has to tell them apart.

Distance does not work, because a long slow drag and a short fast flick can cover similar ground. Total duration does not work either, since a flick preceded by a moment's hesitation reads as slow.

What works is the speed the finger was travelling at the moment it lifted. A real flick clears well over a thousand pixels a second; a deliberate drag runs at a few hundred. Measuring velocity at release separates them cleanly.

The landscape problem

A bar of controls across the bottom is fine in portrait. In landscape, on a phone about 390 pixels tall, it leaves nothing for a twenty-row well: the cells end up around ten pixels.

So in landscape the controls split into two thumb clusters at the left and right edges, and the layout takes its reserved space from the horizontal axis instead. The well keeps the middle of the screen.

The rest

Overlays can be scrolled while the playfield stays locked. Heights track the address bar as it collapses. On-screen buttons never trigger the browser's long-press menu. None of these are visible when they work, and all of them are maddening when they do not.

Read next

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• The Four Game ModesMarathon, versus CPU, split-screen and online duels, and what each is actually for.
• Every Control in TETERIThe complete list for keyboard, touch and gamepad, including the ones that are not obvious.
• Playing Offline and Installing ItA service worker caches the whole game, so it runs with no connection and can be added to your home screen.
• Where the Name "Tetris" Comes FromA Greek numeral prefix welded to the name of a racquet sport, because the author liked both.
• The Arcade Versions and What They ChangedA coin-op cabinet has different incentives to a home console, and the design shifted to match.