Iwament
Publish chess. Leave the IQ claim out.
Chess is on HD Games because the rules are deep and already shared. Reviews of school chess lessons do not show that the game reliably lifts general ability, reading, or mathematics once the comparison is fair.
Chess is an easy game to oversell. The board looks like thinking made visible, so the game gets recruited as a treatment for mathematics, reading, and intelligence. The studies do not support that recruitment.
Giovanni Sala and Fernand Gobet reviewed chess-instruction studies in 2016. The average effect on academic and cognitive measures was modest, a little larger for mathematics than for reading, and longer programmes tended to look better. Almost none of the studies had the design that would settle the question: a pre-test, random assignment, and an active control group doing some other engaging activity. Without that, novelty and expectation can look like an effect of chess.
Their 2017 review set chess beside music training and working-memory training. The pattern was the same. Where the comparison group did another real activity, the advantage shrank toward nothing. Separate experiments that did include an active control group did not find a clear gain in mathematical problem solving.
HD Games includes Chess. The reason to publish it is the game: a shared board, a hard position, a way to play a person or a bot. Getting better at that game is already a sufficient outcome. Far transfer, the hope that skill in one domain lifts an unrelated skill, is rare, and this studio will not advertise Chess as brain training.
The same limit covers the rest of the catalogue. Checkers, Reversi, and Mastermind reward attention to the position in front of you. That is the skill on offer.
Sources: Sala and Gobet, Educational Research Review, 2016; Sala and Gobet, Current Directions in Psychological Science, 2017.