Question: May one play Scrabble on Shabbos?
Answer: There are a few potential issues with playing Scrabble on Shabbos. The first is whether forming the letters into words is considered kesiva, writing (and mechika, erasing, when breaking up words).
The Levush (340:4) writes that one mustn’t open or close a book on Shabbos if there are words stamped on the edges of its pages. Doing so will form or erase the words, which may be forbidden midoraisa! Likewise, putting letters together to form a word in a game is forbidden.
The Machtzis Hashekel (340:6) extends this prohibition to picture jigsaws, as one mustn’t create or ruin a picture.
The Taz (OC 340:2) disagrees, comparing opening and closing a book to opening and closing a door which isn’t considered building or destroying. While we don’t Pasken like the Levush, the Mishna Berura (340:17) writes that one should avoid such books if possible.
R’ Tzvi Pesach Frank (Har Tzvi – Tel Harim, Koseiv 4) argues that the Levush only forbids using such books as the letters themselves are formed or erased, though would allow joining letters together to form words. Thus, R’ Yehoshua Kaganoff maintains that even the Levush would permit playing scrabble, where the letters are already formed (See Chazon Ish (OC 61:1) who prohibits eating cake with writing on if doing so will destroy a letter).
R' Yisroel Pinchos Bodner (Tiltulei Shabbos 1:n24) writes that R’ Moshe Feinstein also forbade playing when the letters are affixed to the board.Yet another issue is playing games which normally involve writing. The Chayei Adam (Shabbos 38:11) forbids playing such games on Shabbos. As one usually records the score while playing Scrabble, one would not be allowed to play on Shabbos (See Bris Olam, Koseiv 13 who questions this and Shemiras Shabbos Kehilchasa 17:31, Igros Moshe OC 5:22:14), though similar games which don’t involve keeping score (such as Junior Scrabble) would be permitted.