In theory. In practice, depends what judge you pull, and you'd better have deep pockets for legal fights.
My friends made a Tetris-like game (under a different name, with unrelated art, just broadly similar rules) and were sued out of existence by The Tetris Company. Even though they were legally in the clear according to theoretical analysis, the judge took a brief look and decided "this seems like it should be a violation" and summarily decided in the Tetris Company's favor, without even engaging with any of the issues involved. Their pro-bono lawyers decided they didn't have the resources to mount an appeal, so that was the end of that.
Tetris Holdings, LLC v. Xio Interactive, Inc. held that the tetrominoes are "expression; they are not part of the ideas, rules, or functions of the game," which certainly seems open to dispute, but I could just as easily imagine the same standard being applied to letter tiles with a score value in the corner.
So yeah, unless you have a few spare million to get this precedent overturned, it's probably not worth it.
Wait what? That’s not expression. Without the blocks being the shapes they are there wouldn’t be a (viable) game, so it’s clearly part of the rules.
Whether the blocks look like jelly or concrete is expression. Or even the exact graphics they use in Tetris.
But the fact there’s blocks in preconfigured shapes (and what those shapes are) is game rules. There’s only so many ways you can stick four blocks together…
Yeah, the judge's gut-feel decision that using tetrominoes is not part of the functional rules of the game seemed absurd to me. But hey, when you are the judge you can more or less decide however you want, and the only one who can say otherwise is the next appellate court.
Disclaimer: I made the "art" for Xio's game (i.e. I picked the colors and drew all the tiles and menu buttons etc. on my laptop in photoshop) as a favor to my friends, so am not an unbiased reporter. As a reward I got to sit through a long deposition. :-)
My friends made a Tetris-like game (under a different name, with unrelated art, just broadly similar rules) and were sued out of existence by The Tetris Company. Even though they were legally in the clear according to theoretical analysis, the judge took a brief look and decided "this seems like it should be a violation" and summarily decided in the Tetris Company's favor, without even engaging with any of the issues involved. Their pro-bono lawyers decided they didn't have the resources to mount an appeal, so that was the end of that.