Checkers is no less intellectually challenging than chess. More options makes the game harder, not easier.

Chess is played with the mind, and all evidence suggests that using our minds in such a way keeps our minds young, and playing chess brings great pleasure, which in turn keeps us healthy...more than just a game I would say!

Monopoly is just a game.  Chess is a lifestyle.

lol. That sounds like an entirely appropriate response...

But it is a game...a sport...a past time...a life long passion...however you see it, it does not change what it is.

You seem to have taken what was  said as an insult, without clearly indicating what was said, and the context in which it was said. You also seemed to suggest that she should have been impressed with you because of the time you invest in chess. Maybe "how" she said it was wrong...maybe there was something in what she said, that you can take and ponder on.

Basketball, football, tennis, checkers, monopoly, chess...they are all "games"...some of their players have made them into careers, and have made a living out of them...but for the majority of these "game players", this is something we love to do...but there are other facets to our lives...I think this is what she was trying to get at...yes we love this sport...but will it pay my bills? Will it provide materially and companionship? Will it provide for all my other needs? I think not...and maybe this is what she was getting at...we need chess in our lives, but there has to be a balance in order for to grow and develop.

Well, everything is what it is -- you can use the same reasoning to dismiss almost anything. 

Different people have different passions in their life and it's rude to dismiss yours the way she did.

Your mom is a game!

But in all seriousness, I think that remarks like that disparage the amount of work and time that many players (and professionals!) put in. For example, football is "just a game", yet multi-million dollar contracts are signed over it. If you went up to a professional football player and he talked about how much time he spent playing football (american football, sorry, should have clarified!) and the amount of time he spent practicing, and you dismissively told him it was just a game, how good would he feel?

Just tell them you don't appreciate the disrespect that is given to your time or work.

Sure, & "life is but a dream."

I don't waste time on reductivist viewpoints...  take that attitude far enough, and it becomes clear that all passion is stupid.

"Chess is not a matter of life and death: it's more important than that."

The internet screens any sarcasm out of your words, but I am pretty sure you are joking right....

you aren't playing chess, chess is playing with you.

I blame the Fibonacci opening.

Tell her psychology is crap!

Monopoly and checkers are just as mentally challenging and intellectual as chess, if not more so. Just because most people might play like novices in those games doesn't mean it has to be like that.

I have seen professional football (soccer) players say football's just a game.

I think OP really may have issues because chess is just a game. At best it's a trivial pursuit that makes us feel good and awakens our spirits, at worst it's a complete nonsense and waste of human life.  

I'd take exception at the word "just".

 ... if you seriously wanted to "smash her in the face"  and are considering ending a friendship because that person doesn't show proper deference to your hobby, you need to consider seeing a psychologist for real. Everyone has a right to their opinion, and she has no more obligation to appreciate the game of chess the way you do than she has the right to insist that you take up knitting or yoga. Although those things may be more theraputic.

 Love the idea!

Tell her that human relationships are just a game, and often fatal.

Of chess it has been said that life is not long enough for it, but that is the fault of life, not chess.

What makes chess any more trivial than anything else in life?