Tell her that you particularly want that game for Christmas then she'd think about prioritizing it over the others.
Also, tell her that "All work and no play makes Jack a dull boy." Just as she invests in your education she should ensure you're able to enjoy your free time as well so you don't spend it seeking fun elsewhere on drugs, smoking, etc.
After all, you have one childhood to enjoy and if she doesn't let you play games now....then later on you will live out your childhood in your adult years and she will have to take care of you (mentally) then.
But anyway, earnestly tell her how you feel. (I've had most of my successes coming from honesty. That and excellent grades and good conduct both at home and school sealed the deal.) If she asks if it's an educational game, tell her not quite. Not everything in this world might be labelled as educational but many things can certainly teach you good values nonetheless. And 'educational' is not a tag that always needs to be attached to something fun. Fun is fun. And Sims is wholesome fun.
