Free smartphone games for travelers

Duolingo: This app doesn't just waste your time -- it's actually productive! Duolingo is a game that teaches you the language of your choice (Spanish, Danish, Irish, French, Italian, German, Portuguese and Dutch are available) in a fun format that doesn't feel like studying. Available for free on Android and Apple iOS.

Candy Crush Saga: This game is so addictive that it spawned a "Time" magazine article about the science behind the app that makes it so compelling. It's free to download and play, but be warned -- it's very tempting to make in-game purchases, which let you advance levels faster. If you've already beaten all 544 levels of Candy Crush Saga, try Candy Crush Soda Saga, just launched by King, the maker of the app. Available for free on Amazon, Android, Apple iOS, and Facebook.

Draw Something Free: It's like a mobile version of Pictionary: You're given an object to draw, and your friend has to guess what you're drawing. There aren't as many words available in the free version of Draw Something as in the paid version, but it's a fun little distraction if you play against different people. Available for free on Android and Apple iOS.

Words With Friends: If you like Scrabble, you'll love Words with Friends, which is basically the same game, except it's free and playable online. You can play random strangers or your friends, and you can message others within the game. Unlike Scrabble, if you play a word that isn't legit, the app won't let you use it, but you won't lose your turn -- you'll just have to try again. Available for free on Amazon, Android, Apple iOS, Facebook, and Windows.

Temple Run And Temple Run 2: "Grab the idol and go!" That's basically the entire premise of Temple Run and its sequel, Temple Run 2. Both games are "endless runners," which means you'll run, jump, slide and dodge your way through a lost temple until you eventually die a horribly gruesome death. Where's the fun? The game's both addictive and rewarding: As you play, you can unlock new characters (including "Montana Smith," who looks very much like another famous globe-trotting archaeologist with a fedora) and new powers to help you beat your previous high score. Available for free on Android, Apple iOS, and Windows.

Dots: Dots is one of the simplest games out there, but it's also one of the most popular. All you have to do is make squares out of same-colored dots. Want to make it more complicated? This guide to winning at Dots should help you out. (But don't let it stress you out. According to the creator of the app, it was designed to induce a "zen-like" state while playing.) Available for free on Android and Apple iOS.

Tetris Blitz: Tetris was habit-forming when you played it on Game Boy back in the day, and now it's even more mobile. Play it for free in Tetris Blitz, a two-minute game in which you have to clear lines in a short amount of time to reach a high score. (The original version of Tetris is not free, but you can download it for $2.99.) Available for free on Amazon, Android, Apple iOS, and Windows.

Cut The Rope Free: The free version of Cut the Rope is basically the same as the paid one, except you have to deal with pop-up ads. To play, use your finger to slice ropes in order to feed Om Nom, a hungry monster. It's a simple but easy time-waster! Available for free on Android and Apple iOS.

MAYDAY! Emergency Landing: Pretend to be a pilot while you wait for your plane to take off with the MAYDAY! Emergency Landing app. In the game, you have to fight dangerous weather and aircraft failures to land a commercial aircraft safely. (Maybe this isn't the best game for nervous flyers.) Available for free on Amazon, Android, and Apple iOS.