Crazyhouse: Chess With Drops

Recently, I've started playing crazyhouse, also known as z-house or ZH, very regularly and I've enjoyed it a lot. Unlike almost every other game I've played, besides Tenjiku Shogi, which is absolutely unmatched, crazyhouse is very fast-paced, with the two main considerations (and possibly the only two considerations) being king safety and attacking potential. 

This is best demonstrated by an example. In the above position, it is black to play and black has 3 knights, a pawn, and a queen in hand. The winning move is N@h3+ (@ denoting a drop). The king cannot run to h1, due to the very pretty Q@g1 Rxg1 Nxf2#, so White must capture. Then N@f3 (one of the main points of a knight sacrifice is to overload the g pawn, the difference between f3 and h3 being that a knight on h3 controls f2) forces Kh1 or Kg2, but which is chosen is inconsequential, as after Kh1 Black must play @g2 (the same as P@g2) to drag the king to g2 anyway. 

This pawn sacrifice to drag the king to a better mating square is called a yo-yo mate (dragging the king forward with checks to make the sequence forcing, followed by pushing it back, a very apt name), and the move that starts it a hook check. 

After Kg2, or Kxg2, Black can simply play N@h4 Kh3 Q@g2#. Although this example seems fanciful, the combination of pieces in hand is actually not too uncommon, and this mate has actually occured in some of my games.

Because of how sharp z-house is, and how important tempi are, often symmetrical positions are completely losing for black. Allowing Bg5 in the Four Knights Italian leads to one of these, so Black must deviate before this point with a move such as Be6 early on. Just as in Tenjiku Shogi, the first player's inherent advantage is much greater than in other games, and in the same way as the old Tenjiku ruleset, White is most likely completely winning (FSF and Multi-Variant Stockfish give +2.8-ish, but these engines often get very confused and evaluate positions incorrectly). I've played some matches against players of a similar or higher strength to myself (1800-2100 lichess), and generally we alternate wins as we alternate colors. Despite this, with some interesting opening choices, I do get some success with Black, and at least for a year or two more, this is still a very fun variant to play. I've found that even minimal experience with longer mate calculation and checkmate patterns helped me gain rating very quickly, so I'm sure stronger shogi players would not find this game very difficult.

In short, you should definitely head over to lichess.org and give crazyhouse a try!