Narik Chess is a chess client that supports a variety of variants, all of which can be played as standalone modes or in combination.

Variants

Conway Chess

Following cellular automata rules, slimes replicate or die, all while acting as obstacles for the players.
 

Multiverse Chess

Traveling back in time through history boards is added as a new dimension that pieces can travel through.  Traveling to a previous board creates a branching timeline that is required to be played on.

Spell Chess 

Engage in a chess wizard battle with limited-use spells.

Duck Chess

At the end of each turn, both players must move a Duck that blocks all movement.  Quack quack!