Why don't you stop doing "the right thing" to get into college, and do what you are genuinely interested in. If you are doing extracurricular activities for the sole purpose of looking good on a college application, that is stupid. There was a student applying to MIT who actually built a fully functional miniature nuclear core on his property while in high school, and for other reasons he was turned down by MIT, one of the most prestigious engineering schools in the world. Likewise, it is not smart to spend your childhood (where you don't have to go to work eight hours a day every weekday the whole year, muster up rent every month, pay bills for everything you use, pay for every meal you eat, pay for everything you do, and still try to find something enjoyable to do) on a checklist of things needed to look good on a college application. In converse, you do not want to waste your time, either. In my opinion, sports are a waste of time if you feel you don't have enough of it. Also, don't fully concentrate on making a game, but keep more important things on your horizon. For example, you could make a game while you are still a sophomore, but do something constructive next year, like use your programming knowledge to study papers and books and maybe do something like make a computer science entry in the Siemen's Science Competition or the like. Not to sound corny, but there is so much one can do in this day and age, yet people tend to squander it chasing for menial and traditional lifestyles (i.e. "I'm just going to take it slow, be married, have a few kids, someone else can do the thinking, I was never good at that, I'm just a simple man/woman").
This, so much. I've come to realize how little grades actually mean. Of course, dropping out of high school is probably not the wisest choice you could make, but working in your own time after school (either coding, or any productive hobby really) means so much more in later life than getting straight A's. Plus, if you can get just that little bit ahead of the game, it makes high school essentially trivial for the subjects you're interested in. For the others.. just churn through it, you get to specialize in a few years.
I never bought into the whole "be the best at school" trend. Mind you, I was never a downright bad student, but in high school I never really strived for perfection, put the absolute minimum amount of effort I could into actual schoolwork, just enough to pass, and ended up with a 70-80% average which got me into university (again, not into a top university, but a decent one, as far as universities go). But this mindset many people would qualify of "lazy" and "unambitious", gave me a ludicrous amount of free time to get ahead in maths and programming - mostly because it was so much more fun than mechanically solving quadratics and integrals in class - and if I had to do it all over again, I would. Without hesitation. Personal satisfaction is so much better than reaching milestones set by society.
Now I completely understand why some people (including you, most likely, Riztro) would look down on me for this, and not everyone has the luck I had, but I am satisfied with the way things have gone so far, at least education-wise. I think the most concise way to put it is that to me, public education is not a goal in and of itself, but is more of a helpful signpost that you only need to read once or twice. I am not advocating this, as I do not have a basis of reference, and I do think it's a decision you have to figure out for yourself anyway. If going to a top college is your goal, then go for it! Just don't go in blindly because "someone told you so".
As for your motivation problem, I've found that a good way to resolve those mental roadblocks is to work on something smaller, much smaller in the meantime, that you can accomplish in, say, an afternoon or two, and get some gratification from completing it. Then you might be in a better mindset to work on your game. Also, I understand this isn't compatible with your schedule but I personally cannot "switch on and off" of projects like that, I need to have a good two-three hours minimum ahead of me to really have time to gear up and become productive. But that may just be me.
Though building nuclear reactors is kind of a risky hobby. Would not take up.
