Typing on mobile devices is typically considered just a necessary evil, a means to achieving a higher end. But it can actually be a great deal of fun, as evidenced by ZType, a game designed by Dominic Szablewski of PhobosLab. Originally developed as a casual browser type-'em-up in 2011, this space shooter was revived for the mobile realm last year, and it's produced one of the most delightful and instantly addictive games on either iOS or Android. The game pits you, a single brave space explorer, against waves upon waves of hostile spaceships. To survive, you have to destroy them first, and that's achieved by typing out the word associated with each enemy.

As simple and intuitive as the gameplay is, it actually took a lot of clever software engineering to make a keyboard that works just right for the game. Every mobile keyboard nowadays has a predictive element that makes typing on small screens a forgiving experience, correcting errors and guessing (often reliably) at the writer's intended meaning. But a game keyboard couldn't be quite as forgiving, and didn't need all the extra baggage of language settings and the like, and so PhobosLab created its own version, which lends the player just enough of a helping hand. This game is frustrating in the best possible way, offering a real challenge that makes beating your high score feel worthwhile and rewarding. It's free to play on iOS, Android, or the web.