The good old Halo series... All those memories with Halo 1 for the PC (never got an xbox so I stuck with the first part on PC). In fact, I was also rather good at it.
For maybe the first time ever here on HW I don't fully agree with Karen, though there is a lot of truth in what she says. First and foremost, you must do what you want to do. Maybe you could ask yourself the question whether what would make you happier in the long, playing Halo 3 or finishing school. While Halo 3 provides more joy now, finishing school might result in a better job and a happier life in the long run. But you decide. Also please try to look at things from the other side as well. Not going to play Halo now might result in regret, but not finishing school now might result in regret too.
I think that is the best you can do, think about it carefully and as objective as possible. It is easy to see that Halo is were your heart lies at the moment, so it's all too easy to start bashin' school and praising the game. Maybe a Halo pro will last for only 2 years, and after that it just might be that your dad decides to quit your funding and you end up the gutter. It could be that you finish school and fall down in a deep depression because you feel like making the wrong choice in the past. You are the only one who is fully aware of the situation, so you choose.
One last thing though. Make your decision in total consciousness. Say to yourself "This is what I want to do know, and no matter how things turn out, I will never regret this choice". In fact, try to say that with every decision you make, so there will be no more regret and thus no more negativity deriving from it.
Take care Spaceman, and I hope to hear from you again!
Erik (also? an 18-year-old Halo addict :) )
Acceptance is the key
The World is but a reflection. Smile, and it will smile back.
Try to keep smiling! :)