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I've been slowly working on a Spell Chess engine since last June. While it's certainly not done, I have made some good progress and the current version could be useful. It certainly sets the table stakes for engine strength. With the recent spike of interest in engines, I'd like to share this preview, in-development version of Frostbite. But first: Fair Play Obviously, you may not use the engine (or the site at all) during a game. All requests are logged as inputs to an automated pipeline to detect engine usage during games. Some information is provided to chess.com, but for fair play security reasons I won't say exactly how this works. Multiple accounts have already been closed in connection with the site, including for cheating with a private beta of this engine. Do not cheat; you will be caught. Play Frostbite This special beta link will allow you to see the Engine tab: https://spellchess.win/?beta=0abf9a6d0bf1  To play against the engine, set "play engine move" to "for white" or "for black." If you just want to analyze a position, press Evaluate Now or check "auto evaluate" (the equivalent of turning on an eval bar). As this is a preview, I might end up disabling the link temporarily or longer-term if there are problems with fair play or server overload. Strength Frostbite does not yet have enough depth to provide broad opening insights. In fact its positional play is sometimes strange, especially with the non-NNUE version. For depth reasons it may also fall into opening traps. But overall, it would be a decently strong player: I think over 2000 if given 5 seconds to think per move. If I play it while distracted doing something else, it crushes me. Even when I'm paying attention, I often lose to it from common openings. A human+computer team with a 2100~ human to guide the engine would very likely be 2500+. Even a weaker version from last August was helpful to me for opening prep (never during games, of course). I hope it's useful to you as a sparring partner and second opinion in analysis. This is version 0.2. My plan is to set the version to 1.0 once it's superhuman, able to consistently beat the strongest players. I hope to make more progress and see others' engines in the coming months.

Yes, I’m not afraid of saying it, you are all noobs until you learn the freeze tactics. So, in good spell chess students that you are, you obviously ask me : “what the heck is a freeze tactic ?” A freeze tactic is a tactic using a freeze spell which consists to attack a piece with a freeze so after he counterfreeze, that piece will next move be in danger and you have time to create a new threat so the opponent cannot deal with both.1. Forced freeze tacticsA forced freeze tactic is a freeze tactic you’re gonna use on the king, which means with a check.Exemple 1 :Consider the following moves :e4 e5Bc4 c6In this position white can play the move :freeze@e7Bxf7 freeze@e6Nf6Because after black freezes back you can firstly play 4.Qf3 which will uncstle the king and bring a positional long term advantage which could be exploited by playing… [very long text…], but you can also play the moves :jump@a2Rxa7 or jump@h2Rxh7And black is in check and will lose a rook and a jump for a bishop, and most importantly, the rook will always cause very annoying problems in the back-rank.Exemple 2 :Consider the following position :Black is attacking the white queen with it’s bishop, toh white can ignore it and play the move :freeze@e7Nxd6 freeze@c5Rf8And after black freezes back as usual (because remember he’s forced or he would lose the game immidiatly), white has many moves but the best, the crushing one, the mating one is :jump@e6Qxf7+#Checkmate ‘cause the queen is protected by the knight, she covers all the king squares, and the king is in double check.Exemple 3 : Consider this endgame position :Black seems completly winning because he has a rook for a bishop, and a pawn ready to get through white’s defense. But black made a mistake : he put all of it’s important pieces in a 3×3 square, and white can play the move :freeze@e7f5+ freeze@f4d3Bh4And this is gonna be a drawable or even winning position for white.Remark : you can also do a freeze tactic with one piece blocking a check because of the threat to take the king with jump.General exemple :Here are all the most commun ideas with a freeze tactic :Thanks for reading this article, if you have questions, reactions, write them in the forum, and I’ll soon write an article on freeze tactics : part 2.@Delhy

I came across this position and won the game in 3 moves. Can you find them?This is maybe 1900 rated if you know to look for a mate My solution is at https://www.chess.com/variants/spell-chess/game/99203845/33/3I searched the position and couldn't find anything better for either player

Chess.com variant server is sometimes a little bugged. In spell chess we already found a bug which is explained on the page linked. But now, i think i have found a new bug (this one won’t have any importance toh, or just for people trying to get nice checkmates). Please consider the very simple following line :e4 e6freeze@c7Bb5 freeze@c5Bb4c3 c6cxb4 cxb5Nc3 Nf6Nxb5 a6freeze@e7Nd6 freeze@e5Nc6Qh5+ Ke7jump@d6Qc5+If you put this line in spellchess.win, it’s gonna add a little # (it’ll be considered as a checkmate), while if you write this line in the variant server, it’s not gonna add the # because it thinks jump@d7Qxd6 removes the piece we jump over and isn’t check anymore.To conclude it seems like chess.com considers that the jump applies on a piece and not on a square.Tell me in the forum what you think of this new bug/rule précision, and new articles soon !@Fleex255@Delhy

Hello, as most of you are aware, I have been developing another spell chess engine in C#, Arctic Rabbit. Recently, it has gotten better and better and is now very strong even at depth 4 (~2s with quiescence). There are plenty of optimizations still possible and I think it could be a promising engine. Currently, it has a tuned handcrafted evaluation since I don't I'm capable of developing an NNUE yet. Since it is only depth 4, it can fall into opening traps early in the game as black, but the tuned PSTs do help prevent many of them.I just tested it against Frostbite and it actually managed to win! Although, it wasn't a terribly interesting game and Frostbite somehow blundered very badly. Arctic Rabbit was white, Frostbite was black. Frostbite was on NNUE, 5s and my engine was set at a depth cap of 4. https://spellchess.win/#!moves=DBwyKgUaNCwDFTsyFRI+LQ0V0T0Z4gQFOSgSETEhGgzKKCIMISIR8yEqEQCzKjwIt also seems to like an interesting opening (as seen in the game) as white against the usual c6, e6, qc7, nf6 setup, which is e4, bc4, qf3, qc3, and f3 which seems promising.I do not have a public version available yet (mostly because I don't know how). I plan on making the project open source soon. I'm curious what you guys think about that as well!

Finally a new spell chess problem, I would say around 2050 level this time.Can you find a move which leads to a checkmate or a king capture ? Write it in the forum !@Noob-AI-81@Delhy

I am and i always be an e5 defender. It’s why today, helped by @AlwaysGetFlagged and @sicilian_defender_I, we searched in the deepest and weirdest lines of e5 to proof it’s WAY BETTER than c6 e6. I am very lazy so I won’t put commentaries for now but I may add some later. Anyway, time for spell chess !e4 e5freeze@c8 Bb5 freeze@b4 Bb4c3 c6cxb4 cxb5Nc3 Nf6Nxb5 O-OQb3 d5Qg3 Bg4h3 Nc6hxg4 Nxb4Qb3 Nd3+Kf1 Nxg4And this is better for black because they can’t stop all the freeze checks and jump mates.e4 e5freeze@c8 Bb5 freeze@b4 Bb4c3 c6cxb4 cxb5Nc3 Nf6Nxb5 O-ONd6 Qb6Qb3 freeze@b2 Qxd6And this might also be better for black.If you’re still not convinced, well tell in the forum the “problematic” lines, and remember nothing is problematic for e5 !@AlwaysGetFlagged@sicilian_defender_I @Delhy

For the past few weeks, I’ve been hacking on a Spell Chess engine as a fun side project. I recently learned the basics of chess engines, and this felt like a cool (and painful) way to apply them. I’ll keep most of the details intentionally vague—I don’t want to take the fun out of this variant—but I’m pretty sure some of you here have tried something similar. Things were going fine… until I hit what I now call Depth 4 Hell. The Wall I Can’t Get PastMy main constraint is simple: 1 second per moveDepth 4 works consistentlyDepth 6 takes ~10 seconds on average, which is a non-starterNo matter what I do, I can’t seem to break past depth 4 without blowing the time budget. The branching factor in Spell Chess is absolutely wild, and every “small optimization” just gets swallowed instantly by the search space. Where I’m At Right NowBasic search is workingEval isn’t amazing, but it’s not terrible eitherMove time is stable at depth 4Anything deeper feels like I need a fundamentally smarter idea, not just micro-optimizationsAt this point I’m mostly curious about other people’s experiences: Has anyone actually pushed past this under tight time limits?Was there a specific breakthrough moment?Or is depth 4 just the reality unless you completely rethink the engine?A Quick Promise to the CommunityJust to be super clear: I promise I will never use this in actual games. The plan is to open-source the project once I’m satisfied with it. Why not now? Honestly—it’s buggy, messy, and I know I can do better. I’d rather share something I’m proud of than dump half-baked code. Would Love a ChatIf you’ve worked on a Spell Chess engine (or anything with a similarly insane branching factor) and made it further than this, I’d love to chat . Mostly to compare notes and hear what actually worked in practice.

Yes, what you're seing is real, the symbolic bar of 2605 has been beaten. Top 20 changes a lot those days but it's the first time in my memory 8chancellor isn't the first anymore. TwoPotionsOneMate is the new top 1 ! I've played against him and i can guarentee you he's really strong. (For the people who want to win the tournament it's time to get up...) I'm gonna list here the new top 20, from the new first to the last : @TwoPotionsOneMate @8chancellor @dmytroilin @EyeoftheTiger1204 @hollyelf @wolyn @jucha00 @pizzaboats @hula_hu @DragonB70 @coryr305 @moro182 @SeadraCheeseChess @ruotsalaineno @Delhy @sicilian_defender_I @Zenych @MonsieurTheGoodest @Fleex255 @jaca_w https://www.chess.com/variants/spell-chess/leaderboards

Have you ever thought that chess.com variant server is completly bugged ? Well you're completly wrong (hum...). I invite you all to share in this forum pictures or stories that proves that chess.com variant server is working PERFECTLY. For exemple, here's an image which is indisputably completly normal. The rook just took a piece through the king... and the knight ? 

The original thread by LongTermFuture was deleted. I'm re-describing this so I have something to link to. Normally in spell chess, capturing the opponent king is allowed even if it would leave you in check. However, there is a bug that prevents the king capture in the specific situation where: the piece you would capture the king with is pinned to your own king, and you are already in check from something else. Consider this (silly) simple position with White to move: White should be able to win by taking the black king with the rook. This is prevented by the bug: the black rook pins the white rook and the black bishop checks the white king. If either the black rook or bishop was not there, White would be able to take the king despite being in check in the final position. Alternatively, if there was a white knight on d4, it could take the black king because it was not pinned. The bug usually comes up when wanting to take the king with a jump, but the conditions for the bug are unrelated to jumps. The technical reason for this behavior is in how the variants client precomputes pinned piece restrictions. When the position is changed by a move or spell, the code looks for pinned pieces and notes the direction in which they are pinned. It also sets an allowBreakPin property to record where captures (of a king) would have to occur to allow moving off the pin line. It should be possible to break a pin if you're capturing the king of the player putting you in check and you are not in check from anyone else (in 4-player variants). There is another variable for which players are putting you in check from which pieces. This is a JavaScript object where the property names (keys) are player IDs. Unfortunately, JavaScript property names are always technically strings even though player IDs are usually stored as numbers. The allowBreakPin logic (to make sure you're capturing the right player's king) uses the === operator to compare player IDs to property names from the checking players variable. This comparison always fails: the text "2" is not the same as the number 2. allowBreakPin therefore never gets filled in if you are in check.

Maybe you have already seen a knight getting sacrfificed on the b4 square. Today I"m gonna try to explain how this attack exactly works and how it is stoppable. Imagine this position :  1. e4 c6 2. Bc4 e 3. c3 Qc7 4. Qe2 b5 5. Bb3 Na6 6. d4Here black is able to play the move : Nb4 ! The idea is the following : once white takes your knight, you're gonna play : 7. cxb4 freeze@d2 Bxb4 Then if white doesn't block the check and do something like : 8. freeze@c5 a3 jump@c6 Qxc1# And you've won. If white blocks with something like : 8. freeze@c5 Nc3 Qxh2 And you'll be up an exhange. If white doesn't take your knight, you will be able to get a freeze tactic on c2 or d3. To get out of those Nb4 sacrifices, you need to be able to castle out of the way when the knight arrives on b4. It's why you need to quickly develop your king side's knight and bishop for white in those positions. Summary : to get the Nb4 sacrifice for black, you need white to have moved his d pawn (here d4), get your queen on c7 and white not being able to castle 'cause your sacrifice would be unuseful and white would just O-O. @Delhy

I have created an opening explorer / database for Spell Chess at spellchess.win. It shows stats on game results from each move that has been played in a position. Filter by rating or player to explore top theory! If you've used opening explorers for regular chess, hopefully the interface is intuitive. Otherwise, scroll down below the board interface for details. After you finish playing a game on chess.com, you can import the PGN4 machine-readable notation into the explorer with the Load PGN4 button. This is useful to find where the game exited common theory. (For the curious, PGN4s being publicly available via players' archives is how I got the data.) Currently the database includes almost all games by 2000+ rated players through the month of August. Other players may have games in the database depending on how often they play high-rated players. Hyperbullet and 1+0 time controls are always excluded. I'll probably load new games every month or two. Let me know if you have any questions. Enjoy!

I had a new idea to fight Bc4 in the c6 e6 main line, tell me in the chat what you think about it. 1. e4 c6 2. Bc4 e6 3. c3 Qc7 4. Bb3 Na6 5. Nf3 Nc5 6. O-O Nxb3 7. Qxb3 e5 #e5 prevents white from pushing his e pawn and also prevents the knight infiltration in e4. In this case e6 was forced at the beginning but the black e pawn could move after getting white's light square bishop. Our next problematic opening will therefor be e4 c6 e5 which completly stops black's e pawn. I'll try to make an article on it as soon as possible. Don't hesitate to tell me which variation i should study then (Nf3, c3, d4, Qf3 Be2...) ! Just another line I looked at today and I'm going to add it tell me what you think about it. 1. e4 c6 2. Bc4 e6 3. c3 Qc7 4. Bb3 Nf6 5. e5 Ne4 6. d4 Na6 7. Nf3 Nb4 8. O-O Nd5

If you are a 2100+ player, you may have wonder how to stop the white knight from entering your position in the c6 e6 main line. Today, I tried to study the most agressive line for white against c6, which is for me Bc4, and tried to refute it or at least fight it and get equality. Chapter 1 : Classical variation (Bc4, c3) We start with : 1. e4 c6 2. Bc4 e6 #Bc4 forces e6 because of the freeze@e7Bxf7 threat. 3. c3 Qc7 #Qc7 attacks the bishop through the c pawn (even if there are tricks) 4. Bb3 Na6 #Na6 prepares Nb4 or Nc5, which can be stop by castling quickly. 5. Nf3 Nc5 6. O-O Nxb3 #Black taking that bishop allows more play on the king's diagonal. 7. Qxb3 b5 #From here white's move order can change, white is building for Ne4 8. d4 Bb7 9. e5 a5 # a5 trying to remove the white's queen from the b file. 10. Nbd2 a4 11. Qc2 c5  # c5 opens the bishop and is trying to get play against white king. 12. Ne4 freeze@d3Bxe4  I am not sure about the last move but i thought this was a pretty good way to get back development and maybe win a piece.  Chapter 2 : Boom boom variation (Bc4 Nf3) The trap : 1. e4 c6 2. Bc4 e6 3. Nf3 b5 # b5 is losing here. 4. jump@e6Bxf7+ Kxf7 5. freeze@e7Ne5+ freeze@e5Nf6 #Black's move doesn't matter much. 6. Qh5+ Ke7 7.Qf7+ Kd6 8. d4 #There's no way to stop Bf4 or Nc4+ e5+ The refutation is to play Bc5 move 3 and freeze@e5Bb4 counter-attack on white's king and after c3 Ke8 white just lost a jump. Don't hesitate to tell me if some of my moves are wrong and I'll modify this article ! I spent some time on this one so I hope you'll enjoy it ! @Delhy

You may wonder what you need to know to get better in Spell chess, and you would be completly justified because Spell chess is one of the hardest chess variants, if not the hardest according to some people. In this article i'm going to present what I think is the knowledge needed every hundred points. If you do not agree, don't hesitate to tell me ! 1500 level : For me, there are two ways to start spell chess : first way, play games without knowing what's going to happen, and discover during the games go on. That's maybe not the most studious way to start but I think it's the funniest. Second way, read the rules ! You would easely find them written in the chat in every game but I will write them again here : Cast a spell before making a move. Spells are limited, recharge after 3 full turns, and you cannot cast the same spell two moves in a row. Use the Jump spell on another piece to hop over like it isn’t there. Or use the Freeze spell to prevent pieces from moving or checking within a 3x3 area of effect. Be careful—any piece, including your own, will freeze if it enters the spell area. Use spells to find a checkmate or king capture ! 1600 level : At this level, there are three things important : deepen what you have already learned by being 1500, understand that every move with a freeze can be countered by a "counter freeze" and learn that a queen on the edge of the board can be captured by a rook by using the jump spell. 1700 level : I wouls say at this level you need to visualize easely the threats created by the jump. It's by playing a lot of games you will get used to look through pieces and become 1800-1900 ! 1800 level : At this level, you need to learn what I name the "freeze bishop attack" or you'll get destroyed. That's a really good opening for white at this level and black need to know how to deel with it. It's why I'll give you the lines here. The trap you might fall into with black : 1. e4 e5 2. freeze@c8 Bb5 freeze@c4 a6 3. Qh5 Ke7 4. Qxe5+ so if I had to explain you think you can win a bishop with the counter freeze and the queen go out for a double attack and you've been destroyed. The real line to not get destroyed is : 2. freeze@c8 Bb5 freeze@c4 Bb4 3. c3 c6. The double attack with Qh5 isn't a threat because you create a counter threat against the white king. This trap is really important so I needed to explain it ! 1900 level : Continue to deepen what you've already learned and start to look at the "high level main line for black" with c6 e6. You have to know that when your opponent use a freeze that can be ignored (all freezes not use on checks), you can freeze the opponent king and check him, and because he used a freeze before, this spell didn't had time to come back and he will be checkmated. 2000 level : When you reach this level you should already a very clear board vision and you will start to be able to beat really good players (2000-2100-2200). I advise you to leearn and play the c6 e6 theory, mostly against good players. For me, this main line is sometimes annoying and I never play it against lower players but against better players this will help you to not get crushed. For me, the best way to farm elo will always be the e4 e5 lines. 2100 level : That's time for you to learn the hardest spell chess tactics. I'm not going to explain everything because it's really hard but you can check the king by freezing him, and even if your opponent counter freeze you can create another threat (on the queen for example) and your opponent can't deal with the check and the other threat at the same time. It's by playing plenty of games you will develop a board vision for the freezes. Also maybe you don't know but we can also use the squares where the opponent has put a jump so you will sometimes be able to double jump to capture a king ! 2200 level : It's also my level, and there's only one thing I'll give you, use this : https://spellchess.win/. That's a datbase created by @Fleex255 where all the 2000 and 2200 games are stored and you can see the percent of win or loss in a position. This will help you to learn openings. Shout out to Fleex for having done this. 2300 level : One last thing you may not know, a spell chess bug noticed by @LongTermFuture, @HowManyCharactersAmIAllow and @Fleex255. That's all I had for you, I hope this helped you ! Again if you do not agree, tell me in the forum (respectfully of course) ! Bye !  Delhy https://www.chess.com/variants/spell-chess https://spellchess.win/ https://www.chess.com/clubs/forum/view/why-is-king-capture-with-jump-not-allowed-here

Merry Christmas everybody ! Suspicious looking puzzle ? Who knows... @hula_hu @Delhy @ whoalsogotviolentlydestroyedbyhula_hu???

Uh no longtermfuture anymore I think... I don't know what happened but I just noticed it... If somebody knows that would be nice to tell precisely what happened...  I hope he will make a new account soon. I'll do an update if I know more later. @Longtermfuture @Delhy https://www.chess.com/variants/spell-chess

Here's a problem from a a game that i think is hard level (2100-2200). Can you find a move that leads to a checkmate or a king capture for black ? Write it in the chat ! Black to move... Other problems soon ! @user578647 @Delhy

White to move and mate in three (a position where you can capture the king counts as M0)This one isn't very hard