Sebastian Półtorak (HalfIsCrayfish)
Sebastian Półtorak, competing online as HalfIsCrayfish, is an International Master with a serious love for speed chess. The username is a bilingual wink: in Polish, "półtora" means "one and a half", so this IM may be exactly one and a half crayfish, or simply a player who refuses to be fully categorized. Either way, his rating does the talking.
Overview
Sebastian prefers bullet chess above all else. He has played over 8,500 rated bullet games, collecting thousands of wins and pushing his rating to a peak of 2997 (2026-03-15). His blitz game is just as dangerous, peaking at 2933 (2026-05-02). These are the kind of numbers that make other online players check their own internet connection.
Playing Style and Personality
Sebastian is a fighter until the very last second. His comeback rate is a stunning 92.33%, and he still wins 44.63% of games even after losing a piece. His one-sided loss rate sits at just 1.38%, meaning he rarely gets blown off the board. In bullet, where most games end in chaos, he averages over 86 moves per win and almost never resigns early. Opponents who expect a quick resignation at move 20 are in for a long night, particularly around 04:00, his best hour of the day to play.
His longest winning streak is 13 games, while his longest losing streak is 14, which suggests he believes in balanced life choices.
Opening Repertoire
Sebastian keeps a loyal opening repertoire. As White he frequently opens with 1.e4 and 1.d4, showing a clear fondness for the Vienna Gambit and the Amar Gambit. As Black he leans on the Caro-Kann Defense and the Sicilian Defense in its Closed Variation. The Caro-Kann Defense alone appears in over 500 of his bullet games, making it a trusted old friend.
A typical Caro-Kann Classical line he revisits often:
.Rivalries
No online career is complete without rivals, and Sebastian has a full cast. His most frequent opponent is Never_walk_alone, who has faced him 160 times. Sebastian leads that series with 87 wins. Another recurring rival is Jeremy Kane, who has scored 45 wins against him and clearly enjoys the challenge. These repeated matchups give his bullet queue the feel of a long-running sports documentary.
Rating Journey
Sebastian's rating story is a steady climb filled with dramatic spikes. In late 2020 he was already a strong blitz player, and by 2026 he touched a blitz peak of 2933 (2026-05-02). His bullet rating followed a similar arc, peaking at 2997 (2026-03-15) in March 2026. The charts below tell the story of a player who treats rating floors as suggestions rather than limits.
By the Numbers
- Most played opponent: never_walk_alone with 160 games and 87 wins.
- Comeback rate: 92.33%, a nightmare for anyone who celebrates too early.
- Average moves per win: 86.12, proof that bullet can still be a marathon.
- Early resignation rate: 0.67, he makes you earn every single point.
- Best hour to play: 04:00, when the rest of the site is asleep.