I typically only put out about 9 cards at a time, to keep students focused. Once they have gone through the letters, you can add new letters.
Students have fun just jumping from letter to letter! For your more advance students, you could also give students a CVC word and have them jump on the 3 letters.
Another fun way to play would be to use plastic frogs and have students "leap" onto a letter and say the letter and/or sound. I've seen these frogs at Wal-Mart, Target, party stores, etc. You can also find them on Amazon here. (affiliate link)
Grab this FREE Lilypad Letters Alphabet Game here!