do I have to pay US customs/tax when buying video games from abroad online?”
I can’t find the official customs ruling, but I seriously doubt you’ll have to pay duty fees. I’ve imported games from Hong Kong and have never had to pay them. The exception is if you order more than $200 worth of stuff. THEN customs can get you with fees, but even then there’s a decent chance your package will slip by. I will say that importing from Japan is always duty free, just in case you ever get anything from there. It’s a bit harder to get a Japanese seller to ship games to you because technically they’re not supposed to. That’s why Amazon.jp won’t ship video games internationally. If you weren’t already using them, Play-Asia.com and YesAsia.com are pretty good HK importing sites. Play-Asia is usually better for video games.