It's said about brain that, "use it or lose it" — now, question being, do you think if person plays brainless gambling games such as slots, dice for major part of his/her daily routine, will it make him/her dull?
I think this reply from @kryptqnick would help profer better answer to this in regards that the both threads is almost in same direction.
I'd say that, in a sense, any gambling tests one's mental skills. Even if it's something like slots or dice, one still needs to be patient, to keep emotions under control, to not overspend and to avoid chasing losses. All of this has an impact on how much is spent on gambling, so it's important to consider. Division into luck-based and skill-based gaming simplifies what's really going on.
In this subject, I don't think if there is at all any game played without mental or logical reasoning.
The slot games are seem to be more likely to be skilless gambling activity but yet, there is terms that being logical can help. So literally, there is no such games that is not required disciplines and there is non that encourages such a dump headed.
What we may not know about unskilled games is that the more we play them is the more our develops mental faculties grows in the logic of finding solutions. So, non of the above mentioned is a brainless game.