How to play:

The first time you play, explain the instructions with an example: tell students you're about to play a game, and decide whether you'd like them to play individually or in groups (I usually play in groups of about 4 students). They just need a piece of paper and something to write with.

I like working with my students to make the first example. I let them pick a letter, and then I tell them we need to make a sentence using as many words as possible that begin with that letter. They'll score a point for each correct word.

In this example, with letter A, we got 8 points:
Los alumnos aprenden árabe con acento andaluz en las acogedoras aulas del aeropuerto.

After the example, students are ready to play. Pick a new letter and give them some time (I like giving them 3 minutes for each round). Remind students that they can include words that start with a different letter (in the "S" example, I use "está"), but they won't get any points for those words.

Once the time is up, they need to share their sentences and count the points. Keep score to make it more fun, and take the opportunity to fix mistakes, review vocabulary and teach new words.

Alternative option:

Instead of giving students a letter, you can give them a prompt they must use to begin, with a few words that use the target letter. This could be a good option to make sure that vocabulary that you're studying in class is present in the game.

For example, if you're doing a lesson on food, you can give them a prompt such as:
La comida de la cafetería...

Students then will try to finish it using as many "c" words as possible:
La comida de la cafetería es caliente y tiene cosas extrañas porque el cocinero colombiano compra ingredientes caros. (6 puntos)