Check constraints for varchar[] and varchar[][] columns in a table

for a Scrabble-like word game using PostgreSQL 9.5 as backend
I am trying to add CHECK constraints to the VARCHAR arrays:

CREATE TABLE words_games (
        gid SERIAL PRIMARY KEY,
        created timestamptz NOT NULL,

        player1 integer REFERENCES words_users(uid) ON DELETE CASCADE NOT NULL,
        player2 integer REFERENCES words_users(uid) ON DELETE CASCADE,

        played1 timestamptz,
        played2 timestamptz,

        hand1 varchar[7] NOT NULL CHECK (ALL(hand1) ~ '^[*A-Z]$'),
        hand2 varchar[7] NOT NULL CHECK (ALL(hand2) ~ '^[*A-Z]$'),
        pile  varchar[116] NOT NULL CHECK (ALL(pile) ~ '^[*A-Z]$'),

        board varchar[15][15] NOT NULL CHECK (ALL(board) ~ '^[.A-Z]$'),
        style integer NOT NULL CHECK (1 <= style AND style <= 4)
);