Flash Duel is a simple, fast card game that simulates a duel between two Fantasy Strike characters. There are 10 characters to choose from (all included), each with three different special abilities. Landing just one hit wins a round, and a game is best three out of five rounds. Games take only a few minutes to play.

The duel takes place along an 18-space linear track. Players draw from a common deck of 25 of numbered cards (five copies of each number 1 through 5), and use these cards to move, attack, dashing strike, block, and push. Each character's special ability cards add a new dimension to the base gameplay, and create 45 different character matchups.

Flash Duel was designed and balanced by David Sirlin, the multiplayer balancer of Street Fighter HD Remix, Puzzle Fighter HD Remix, Kongai, Yomi, and Puzzle Strike. The core gameplay was inspired by Reiner Knizia's game En Garde.

This game has received a follow-up in Flash Duel: Second Edition, which adds 10 new characters, slight balance changes to the original characters, support for up to 5 players, and new gameplay modes