The patent covers the game board and some variations that are specified for such a board.

Give https://patents.google.com/patent/US7264242B2/en a read and see if that describes the computer game. If not, it's something different.

    1. Field of the Invention

    The present invention relates to board type games played on a game board or surface, preferably a substantially orthogonally gridded, planar surface, and more particularly to a game which selectively diverts a beam (e.g. laser beam) by user-placed mirrored game pieces that are moved laterally or rotated during play.

    2. Description of the Related Art

    Many board games have been provided which use paths across their surface as part of the game. An example of such a game is chess. In addition, games exist that depend on the deflection or reflection of objects off of other objects to “score” points.
    The following US Patents are examples of board games, each hereby incorporated herein by reference: U.S. Pat. Nos. 3,516,671; 5,145,182; and 6,702,286.

Going into the patent citations there are a number of other laser board games that it references that are different games with different claims as to what they patent. Here's a different board game with lasers that predates Khet - https://patents.google.com/patent/US5145182A/en

Is it different? Do they claim different things? Having something similar isn't necessarily legally similar.

Blue and Gray is a checkers game that is played on a checkers board with checkers pieces and is distinct enough to receive a patent.

Trademarks protect names. Copyrights protect that text or music or ... Patents protect that idea - the rules and mechanics of that game.

    The game of the present invention generates a “beam” for each player, which can be a low-powered laser diodes to emit a beam of colored light. These beams are reflected and deflected around the playing field by mirrored surfaces of pieces, or stopped by non-mirrored surfaces of pieces.

    The game is won by a player who strategically maneuvers pieces to reflect a laser beam so as to illuminate a key piece belonging to his opponent, e.g., a “Pharaoh” or “King” piece.

    With each turn, a player may move one of his pieces to one of the potentially eight, unoccupied adjacent squares (front, back, left, right or diagonal) or may rotate (re-orient) one of his pieces.

    After moving or rotating a piece, that player presses a fire button that triggers the emission of a beam above and parallel to the playing surface. If the beam hits a non-mirrored surface of a playing piece, that piece is removed from the board and eliminated from further play, unless it is the key piece, e.g., “King” or “Pharaoh” piece, in which case the game ends.

    The pieces can vary in design and setup, with mirrors being located on multiple (e.g. one, two or more) sides or no sides.

And more specifically the claim about movement:

    39. A method of playing a game by opposed players; said game comprising two sets of distinguishable playing pieces, each set having movable pieces with no mirrored surfaces, of which one is a key piece, and pieces with at least one mirrored surface, a game board consisting of a first end, a second end, and a plurality of rows and columns, intersecting to form a plurality of spaces, the method comprising the steps of:

    placing each player's set of playing pieces on the game in a pre-determined starting configuration; and
    alternating turns, each turn comprising moving, either a translation or a rotation, a piece followed by activation of a laser, said alternating moves continuing until one player illuminates the opposing player's key piece;
    wherein moving a piece consists of a movement one space in a horizontal, vertical, or diagonal direction to an unoccupied adjacent space.

Does that describe Laser Chess?