You're probably at least somewhat familiar with Scramble With Friends. Similar to Zynga's Words With Friends, you trade knowledge and skill of a wordsmith against your friends, or random online opponents.
This isn't a new game by any means. It's just one we haven't featured often here at Kotaku, but one that I'm still completely obsessed with. There are stacks of letters, and you can connect them to form words for varying points. The more complex the word, the higher your score.
You can select from a few power-ups to help in your word-formulating process. I like Inspiration best, because it fills in the blanks my brain sometimes gets between words. If you prefer to be less stressed and have more time, Freeze helps you there. Scramble will rearrange the set of letters on your screen. I like that power-up in theory, but the fresh slate seems more distracting than helpful.
I like Scramble because it's simple, yet addictive. It's one of those games that I instantly create 20 different rounds of, just to get my fill.
Scramble becomes a game of speed, where your eyes can recognise words as fast as your fingers can swipe them out. After playing it for a few weeks, my letter-combining skills have significantly improved. There's no better feeling than becoming more successful at something you spend even just idle moments on.