I love your story! Your query, however, definitely needs work.
I think you focus on the wrong elements, rather the important ones.
I'll return the favor asap, promise.
Dear (name of agent):
When sixteen-year-old, hardcore gamer Malory seeks her best friends’ help in setting a video game, she knows it could lead to a fatal error. Part of this error is that they all dematerialize and get sucked into the game. Malory must face it: she hasn’t really leveled up as a heroine. I love the voice, but this can definitely be shortened. Try something like: "When sixteen-year-old, hardcore gamer Malory seeks her best friends’ help in setting a video game, she knows they could all dematerialize and get sucked into the game. Malory must face it: she hasn’t really leveled up as a heroine."
Like the coward she is, she tricked her best friends into an alternate world, that she accidentally locked up in a DVD-Rom long ago. Malory has been hooked on this world for years without anyone knowing. Anyone except J-L, the mysterious boss of the game. He twisted Malory’s dream so far beyond nightmare that she no longer feels up to facing him alone. She remembers a time when cupcakes were not swarming with cockroaches, when meadows were not haunted by sneaky monsters, when the sun rose, when innocents were not found dead. And when there were not slaves her age watching her every move. This definitely need some clearing. Why is she so hooked on this world? Why is the boss twisting her dreams? Can't she just close the game? I feel like you should focus on Why she wants to beat the boss and why she can't let go of it, more.
Malory can’t understand how it all has come to this. One thing’s for sure, there’s no rage quit about it: she and her two best friends have to beat J-L if they want a chance to return home. Such a nice friend... As Malory tries to guide them through, they gather items revealing pieces of Malory’s childhood. They realize these are keys to complete the game . . . but also weapons for J-L to use. I love this.
Malory is determined to restore her game no matter the cost. Restore the game? If only she could see that her guilt and fears are fueling her own game, she could keep it from feeding on her best friends as well. She could expose J-L and understand why he became the boss before he destroys every inch of them. Reword. Malory is determined to do that before the game and the boss feeds on her friends/blabla/blabla. Something like that.
MADNESS RIDERS: THE HERO SYNDROME (62,390 words) is a YA dark fantasy. My concept is similar to Heir Apparent and Dreamscape: Saving Alex but with a darker edge. This will appeal to fans of fantasy and gamers alike.
I’m currently studying French language and literature.
Whenever I can I run writing, art and computer workshops for children. My first publication is a collection of dark erotica short stories titled Les Agonies de l’Innocence (Tabou Editions, June 2013).
Thank you very much for your time and attention.