I play almost all of them, but most are difficult to find, and this is why Poker Stars will ALWAYS be the best online site, and its not even close... because they offer the most games BY FAR.
But even Poker Stars is not perfect... they used to offer 10-Game back in the day, however, at some point in the past decade, after we Americans were banned from playing there by our own damn government, Stars decided to reduce their 10-Game to 8-Game.
And when they did so, they removed my absolute favorite variants... today, the 8-Game no longer has a round of Badugi, nor does it have a round of No Limit 2-7 Lowball Single Draw. 8-Game is still fun of course, but 10-Game was THE NUTS. And its gone for good, apparently. By the time we Americans were allowed back onto the play money side of Stars around 2015, only 8-Game could be found.
And by the way, Badugi is the easiest "oddball" variant of poker... its a 4-card lowball game, with 3 draws (so there are 4 betting rounds), and the nut hand is A234, straights don't count, but pairs do count and pairing up is no good... but the really unique feature of Badugi is that a "Badugi" consists of 4 cards where each card must be a different suit. If you have 3 suits (meaning one of your cards is a duplicate suit of another), that is called a 3-card badugi and it can still win at showdown over a higher 3-card badugi. I love this game, but it is very hard to find, only Stars runs it (that I know of anyway).