Animal, Vegetal, Mineral?
"Animal, Vegetable, Mineral", "Twenty Questions" and "Who am I?" are other classic games you can easily turn into a Spanish guessing game. In most cases you'll be the one giving clues while the students take turns asking questions to figure out who or what you are, although you can also have individual students pick something or someone that they recently learned about or read about in class materials and try to stump the class.
All three games are similar, but there are a few differences:
Animal, Vegetable, Mineral: Give students a set number of questions they can ask before having to guess what you are. Except for the first question, which is traditionally "Are you an animal, a vegetable or a mineral?", all other questions must be answerable with a yes or a no. Obviously, your choices of what to "be" for this game are limited to animals, vegetables and minerals.
Twenty Questions: Just like Animal, Vegetable, Mineral except that the students are automatically limited to twenty questions before guessing, your choices of what to "be" aren't limited, and all questions must be answerable with a yes or no. So multiple-option questions like "Are you an animal, a vegetable or a mineral?" are not allowed, but asking, "Are you alive?" or "Are you smaller than a breadbox?" is okay.
Who am I?: You select a famous character from history--ideally a Spanish speaker, or someone key in the history of a Spanish country--and your students try to guess who you are. They can ask you anything that's answerable with yes or no, and you have to answer truthfully.