Crown Duels is 2-player duel game, where players assume control of the corrupt royalty from Regicide. Like Regicide, it’s played with a standard 52-card deck. Don armour and weapons, cast spells and empower your equipment as you slowly become corrupt and unleash an epic beatdown on your opponent.
Rules are here: https://boardgamegeek.com/filepage/317525/crown-duels-a4-rulebook
This is evidentially a head-to-head game with thematic ties to the rules of Regicide, but extremely different in terms of gameplay. (BGG is currently suggesting that it “Reimplements Regicide”, but that’s clearly not true.)