Tell her that if she can't respect that you like what you like and dont like what you dont like, then you can't give her the same courtesy in return.
My boyfriend and my both love games and there are a few places our taste in them overlaps, but for the most part we have completely different taste in games. Sometimes we make a deal. An "i'll try this if you try that" and most of the time we agree that we don't like each other's games but appreciate that we both tried.
When we were younger-about your age, actually, and Oblivion came out, I got very addicted to it. My boyfriend developed a deep loathing for the game because of this and we had a lot of fights over the amount of time I spent on the game when he wanted my attention. I was able to point out the hypocrisy of this later when he went apeshit over KH2 when it was released and obsessed over it.
We discussed it and sheepishly agreed we were both jackasses about it and since then, our gaming relationship has been a lot smoother. We don;t really bother each other over games only one of us likes, and enjoy discussing/playing games that we both enjoy.
If the relationship is worth it, discuss respecting each others tastes. If it happens in gaming it;s likely to happen elsewhere sometimes too and it's best to have the discussion now. If the relationship goes long term like mine did, it'll be very worth it in the long run. The silly lesson we learned over our games was easily applied on arguments we had later and we've been together for 7 years.
Quick edit: don't call her stuff "kiddy shit" regardless of your feelings about it. Especially not to her face. Be respectful to her if you want her to be respectful to you.