The game Tangram has been in existence for 2000 years and has no copyright, because copyright expires after 70 years after the death of the author.

So making the game Tangram is allowed, but literally copying the Puzzle Assignments from my game Twisting Tangrams for the game Travel Tangram is not allowed and is plagiarism.

it's the same as writing a book, more people do this so this is allowed, but it's not allowed to literally copy texts from other books and use this for your own book and to earn money with your book, because this is plagiarism.

You can see the evidence at the Puzzle Assignments: Boat Puzzles, Squares Puzzles, Triangle Puzzles, Parallelogram Puzzles and the Geometric Puzzles by following the colors.