Wizards duel with their hands, and the right run of gestures is a spell.
Richard Bartle's 1977 pencil-and-paper duel, free in your browser. Each turn every wizard chooses a gesture for each hand, and all are shown together. A Fireball is F-S-S-D-D on one hand, and a Shield is a single palm. Play the bot, or open a table for up to a dozen wizards and play by turns.
With a code you can take a seat if one is free, or watch from the Peanut Gallery.