Note: For now I think the most important things are expanding my imagination of what's possible, developing solid foundational skills (but not doing overkill), finding friends (high in intelligence+openness) to hang out with, and learning what I'm good at and what I'm not. What I regret is getting too obsessed with social signalling.

Also keep in mind that there are a lot of things I would have done differently if I could have relived my life again. My life now is ok, but it could have been a lot better if I made better decisions (but I have to also remind myself that it could be a lot worse, in the sense of ending up in a position where I was wasting years of my life in dead ends).

• Persuading my parents to finally get me Age of Empires II. In all honesty, while it's "educational" for the history (and probably contributed to my 5's in AP World History and AP Euro), I'm not sure if the history I learned from it was all that useful (I really think that I could have spent my time learning more useful things, rather than history). But what was really rewarding about it was that it had a huge dedicated Internet community at Age of Kings Heaven, which I eventually became a prominent user at, and which introduced me to a huge community of very intelligent people who I learned a lot from. I don't think it would have been easy to find another gaming community whose members were as intelligent as those at AoKH (some who inspired me to take the SATs in 8th grade later [for CTY]). It was a golden find.

The more I think about it, the more I realize that my AoKH days were times when people actually valued me and considered me pleasant to interact with.  I was very well-respected there - not due to my AoK skills (since I wasn't great at the game) - but rather my contributions to the community. I joined a clan and became well known for recruiting other people to the clan (and I'm noticing that this is a particular talent of mine). I was also voted as the "nicest forumer" way back when I was 12, and it helps me remember that me being nice to people was actually a real strength I used to have. It's hard to find stories of other people you know (especially those who were older and more experienced than me), but this was the place where I read them.

I also got to see clan politics in action, which was also really interesting - almost a precursor to the types of politics you see later in a real-life environment.

They were the days before I became neurotic, self-centered, and obsessive about academics, and I feel that I've lost a lot by being so obsessive over them. When I think about how many years of "social experience" that I've really had, I count the AoKH years among them (with a huge gap for the year where I became neurotic and obsessed with maintaining an academic image of myself - a gap that finally ended when I joined Quora).

Was there a risk that I could have spent too much time playing Age of Empires II? Yes. Certainly, playing too many custom scenarios like castle blood/germs blood is a waste (it's something I'm tempted to do given that I'm not great at random maps). Also, I really don't think I would have gotten much lasting value from playing numerous 1v1 games and becoming an "expert". I'm glad I didn't do either of those too much, and I'm glad I got involved with the community more.

Also, what I did really reminds me of this: Alex K. Chen's answer to What is the single insight that most changed your life?. I excelled not due to competition, but rather due to having a very unique skillset that made me feel highly valued in my community. There were parts of that skillset (like emotional stability) that I later lost when I later became hyper-obsessive about academics.

Also, it helped me build up a rich repertoire of social experiences. This is an extremely important thing when it comes to developing one's imagination of what works and what doesn't. After all... as Temple Grandin said...

One  of the keys to becoming socially adept and being able to understand the  social rules of relationships is getting out in the world and gaining  experience. And, that means taking risks and making mistakes. It's just  something you have to accept and push yourself on, even though it might  cause some anxiety. I remember talking to a young autistic man about  fifteen years ago. He spent his days locked away in his room reading all  sorts of mag-azines, because he thought if he took in enough  information he'd be able to think in social ways. He didn't realize that  he had to get out and experience the world first-hand, and that he had  to learn how to be in the play.
The only way you're going to learn  is by doing, you've got to get on the stage and act, even if it means  making mistakes. You could look at that as an unwritten rule of social  relationships specifical-ly for people with ASD—I don't know how much  this is actually verbalized to children with ASD because neurotypicals  can learn by observation, by reading, through the experiences of others.  Not so for the majority of us on the spectrum. "

• Going vegetarian (and later using my vegetarianism to reduce my calorie consumption). People often comment on how amazing my skin is and how incredibly young I look. I've never dealt with acne in my entire life. And I think I'll only be more glad I made this decision come 10 years time. Also, vegetarianism helps decrease IGF1 levels (though low IGF1/mTOR signalling during adolescence might be bad for one's brain development). See Alex K. Chen's answer to What is your diet like? for more.
  
• Developing a huge online profile and making myself extremely stalkable on the Internet (see Alex K. Chen's answer to What is the secret to finding the right peers? ). I met so many amazing people that way, and they've changed me, especially in helping me discover what I ultimately value in life.
• Taking the SAT in 8th grade. It opened up so many new possibilities.
  
• Dropping out of school for early entrance at UWashington (also see What are the benefits of going to college at 16?). The biggest benefit of the program is (a) that I got to drop out of high school and to have the freedom to fuck up and explore my interests/strengths with impunity (without selling my soul for the constant social signalling in the last two years of HS), and (b) it makes it so much easier for you to find a few friends among other UW students (even though I was still more antisocial than most). While I also lost the chance of applying to HYPSMC [note that I would choose UW over any school other than HYPSMC], applying for HYPSMC is like playing Russian Roulette, and the risks (especially given that I'm Asian, albeit a very uncharacteristic one) are really not worth wasting 2 of the most incredibly formative years of my life on high school. There's also no guarantee that I would have enjoyed HYPSMC more than UW.
• But I regret not dropping out earlier. School is one of the most toxic/insulated environments that exists, and prevents you from developing the rich repertoire of skills needed for self-development. It also insulates you from taking responsibility for your own learning and for your own decisions.
  
• Discovering Quora (though I think my personality is such that I would have discovered Quora irrespective of whatever the hell I would have done). Obviously, this changed my life. It also changed my value system too - my values are becoming more Silicon Valley-esque and maybe less academia-esque.
• Sniping an Asus laptop off of eBay. I wish I bought a fast laptop for my first year of college though.
  
• [this remains to be seen, but could be after some time]: Couchsurfing the East Coast (BOS+NYC+Princeton+Research Triangle+Livingston, NJ) in 2015 (mid-November-early January), which made me interact with a lot of my Quora friends IRL for the first time (you get so much more out of interactions when couchsurfing), and which led to me moving to Cambridge.

[if you want to see more gory details of what I used to consider "good decisions of my life", view my edit log. In retrospect, I'm not completely sure if some of those decisions were the "best" of my life given that they only contributed to my academic obsessiveness, and I'm realizing that maybe I would be better off if i wasn't so academically obsessed]. My academic obsession was justifiable to the point that it made me value smart people [1] and helped me get into an early entrance program that allowed me to drop out of school 2 years early (which is, IMO, the main benefit of early entrance programs, as I know that I would have been even more emotionally stunted in high school). Beyond that, it created a lot of unnecessary wasted stress that also delayed my self-development. See Alex K. Chen's answer to What is the one piece of life advice you wish someone could have told you when you were younger?, Alex K. Chen's answer to What are the best ways for a teenager to spend his/her time?, and Alex K. Chen's answer to As a teenager, what's the least productive way to spend one's time? for more

[1] But they don't have to be from College Confidential or from elite colleges. HeavenGames/Quora/other online communities is good enough.