Crazyhouse Strategy & Advice

Sacing the queen makes the game interesting

I'm over 1900 on chess.com crazyhouse. My chess rating is...lower

1: King safety. The game is mostly about king safety. Material matters only to attack and defend kings. Defensively controlling squares around your king is critical. Attacks often start with pawn drops or knight sacs near the enemy king to open up a weakness on a color, and then dropping pawns onto that color, that the enemy could only eliminate by sacrificing a piece for the pawn. Weak opponents will tend to just retreat further and die immediately. Stronger opponents will tend to sacrifice for the pawn and tempo and then try to counterattack or defend that color more.

Castling is not always good. Sometimes the king is safer in the center with a queen moved directly in front of it, and rooks still in the corners covering the back rank. Do not allow holes to exist on your 2nd rank. Dropping pawns there (or pieces if needed) to fill the hole is important. Castling can be good if an attack has started and it gets you to safety. It can be worth sacrificing material to just castle out of the attack. If they spent a tempo advancing that pawn and promoting to a queen, but your king is now in the other corner and you are counterattacking, their material advantage might not matter.

2: Piece valuations: P=1 N=B=R=2 Q=4 imo.
Basically pawn is way stronger than normal. Queen for 2 pieces is fair.

Saccing a piece for two pawns and getting any other compensation at all (even 'not having to retreat the piece') is good. If your piece is threatened by a pawn it is often better to take the pawn, and force them to spend a tempo taking back, than to retreat it. Two pawns is often better than a piece.

If your queen is attacked by a piece, and either player is under attack, it is often better to 
sac the queen for the piece and tempo, than to retreat it and keep getting chased around.

Because its so easy to chase around a queen for tempo by dropping new pieces, and because a tempo is so valuable, its important to only use a queen for defense, or to drop it in a strong attack (often to deliver mate).

3: Minor Pieces
Rook is not better than other minor pieces because there is no endgame, and its mostly useful for mating patterns.

Bishop is great defensively. If you are becoming weak on a color near your king, dropping defensive bishops can be key. Bishops on the third rank that both pressure from long range and defend your back two ranks are strong. In an early midgame before attacks have started if you don't know what to do, dropping a defensive bishop on the side your king might castle can be good.

Knight is versatile but probably the best attacker. You can drop it on the color you control near their king, to attack the other color. Or on the color you still control near your king, to defend the color your opponent is attacking on.

3: Keep placing pieces!
Make sure to not built up material in your hand and instead get it back onto the board whenever you can. Rather than move your bishop from c1 to g5 to attack, leave the bishop on c1 and drop a new bishop on f4 instead. Don't push non center pawns, just drop pawns you have captured. Drop bishops on the 3rd rank. Drop a pawn on f3/f6 for more defense (even when you still have another pawn behind it on f2/f7.

Any time you can place material and the opponent has to respond, so it doesn't cost you tempo, is usually good.

4: Pawns
Pawns are strong! 
Dropping pawns on squares you control in enemy territory and forming pawn chains can lock you into control of one color. Then you just need to eliminate defenders that can defend the other color, and drop a knight/rook/queen to finish them.

Pawn attacks are much stronger than attacks from pieces. For example, my bishop attacks your knight. You drop a piece to defend your knight with a knight/bishop. I take, you take back. I drop the captured piece to attack it again. You drop the piece to defend. You can keep doing this to force a repetition or force me to do something else.
You cant do this against pawn attacks.

Dropping a pawn on the 3rd/6th rank a/h file against a castled king is a great way to start an attack. Dropping pawns onto an undefended hole on enemy 2nd rank that threatens to take a piece and promote can be extremely strong. Dropping a series of pawns in an advancing pawn chain forward towards the area of the enemy king can be very strong (for example, after you 'sacrificed' a piece for two pawns).

6: Tempo
Tempo is huge and gets more and more important as the game goes on and kings get unsafe.
If you are under pressure, you have to counterattack to have a chance. You have to make them unsafe as well. Once both kings are unsafe, tempo is so important that just recapturing material in a way that is not check is often bad.

For example, during an attack, after a series of checks, your opponent just drops a piece that threatens your queen. Ignore it and counterattack with checks of your own. Or sac the queen for their piece and then attack.

Another example: Both kings are under attack. Opponent drops a pawn on g7 which threatens to take your rook and promote to a queen, but not with check. Ignore it and attack instead.

If both players have no pieces in hand, tempo isn't that big, its more like normal chess. If both players have lots of material in hand a tempo might be the entire game, as both players might be able to force mate if it was their turn.

7: Sacrificing
Sacrificing is good, especially if the enemy king has to retake, and it is better the more material that both players have built up in their hand.

If your king is unsafe, and you get turn where you are not in check or immediately threatened with mate, consider sacrificing with check or with their king having to come out to recapture. The correct move is probably either this, or dropping a piece defensively that controls your weak squares near your king.

8: Overdefend your king before attacking if the attack isn't immediately strong. If both players only have a couple pieces in hand, and kings are not yet exposed, maybe don't start off by sacrificing material. Instead, drop a bishop on the 3rd rank that defends and points towards their king and also defends the area near your king. Build a pawn chain forward. Drop a pawn to fill a hole in your position and cover more squares.

9: When you are behind
When you get behind don't give up, counterattack. Sacrifice material and focus on tempo. Respond to that threat on your queen by saccing it for the piece and when they pause to recapture, attack.

10: Openings
Openings are tough in crazyhouse, especially as black. Many standard chess openings don't work. Most gambits are bad because the opponent can immediately take the sacrificed pawn and just defend with it. Openings that move a/b/c/f/g/h are bad. For example, I like the Caro Kann in chess, but moving c6 in crazyhouse is bad. They simply control the square from a distance with a bishop or something and then drop a pawn there. The french defense works pretty well as black in my experience, just continually focus on reinforcing your dark squares. Don't move non center pawns! It is even worse to bring your queen out early in crazyhouse than in normal chess. It will simply get chased around by piece drops.

Look for times in the opening where you can drop material to gain an advantage that would not normally be possible in normal chess.

Great insight @Alexfrog0

I never thought about Queen equals two minor pieces or Bishop, Knight, Rook all same value, but it makes sense when I think about it.

Knights are more valuable because they can't be blocked by anything including drops. Sacrificing a bishop for a knight is usually a good deal for this reason.

Drop pieces into a spot that will lure the king or queen to capture it so that you can then fork them with a knight that you drop onto the perfect spot.

I have no idea how to play it but I recommend trying to trap as many of your opponents pieces as possible and try to destroy your opponents pawn structure since that is the most fragile in crazyhouse you can't really attack your opponent or sacrifice the prices unless they over exend or damage it space is really important for crazy house from what I've seen (I could be wrong but here you go)