I love word games of all shapes and sizes, and Flow State Media's collection certainly boasts both.

Free on the Google Play Store, 4 Letter Words is just one in five games in a series, all released at the same time.

There's also 3 Letter Words, 5 Letter Words, 6 Letter Words, and 7 Letter Words.

I was introduced to the series at this week's Apps World in San Francisco and have quite enjoyed them.

4 Letter Words, and others in the series, presents the corresponding number of letters and asks you to piece them together to form the word.

Sometimes there will be more than one possible word, in which case the game will let you know.

Either way, you always have to use every letter.

You're playing against the clock, too, so you have to throw words together fast, making the series as much about reflexes as it is vocabulary.

As you'd imagine, the difficulty stacks with each added letter.

I've found 4 Letter Words is a good starting place if you want a decent challenge and relatively swift gameplay.

While 5 Letter Words is where things really take off in terms of difficulty, don't let the smaller letter word games fool you.

These games aren't afraid to put obscure words to use, and you might find yourself surprisingly stumped at some of the vocabulary presented. Even in 3 Letter Words.

Each game is free on the Google Play Store. You can find them all on Flow State Media's developer page.