I go to a chess event 2-3 times a month in the city where I live, and there are a few of us that are big into variants and play a lot of Bughouse, Crazyhouse, Racing Kings, etc. 960 is a bunch of fun but asymmetrical 960 is a blast, and asymmetrical Bughouse 960 / Crazyhouse 960 is the most fun and hard version of chess I've ever played. There is no theory, just pure tactics and reaction.