The Witcher: Versus

About

The Witcher: Versus (initially called The Witcher: DuelMail) was a free Flash-based multiplayer fighting browser game, developed for CD Projekt RED by one2tribe, that has you create a character from one of three classes and challenge other players to deadly battles.

The game was later ported from webBrowser to iOS in 2011. Since 2014 however both versions aren't playable anymore and the game is considered delisted.

Source: IGDB