(I think this was adapted from a US TV show)
Think about some words which you’d like your students to remember and write them on the bottom of a 3 line Word table. Then decide on a riddle which could result in that word and a score for the relative difficulty of guessing the answer through the riddle. Your cards should look something like this e.g.:
|I am a hundred years|
|Open me in the morning and close me at night.|
Distribute the cards to pairs so that each pair has about 5 cards of different scores. The first pair in the circle can choose who to ask: “Igor and Petra, how many points have you got?” Igor or Petra reply, “We’ve got 4, 6, 3 and 8 points.” The first pair then chooses which riddle they want according to point number and Igor and Petra present the riddle “I am a hundred years”. The first pair has perhaps 30 seconds in which to answer, if they get it, they win the number of points on the card, if not, it’s open to all and the first pair to answer wins half the points.
Continue in the same vein.
You might try getting students to create their own cards too.