Actual New Yorker here (born and raised, still live here). I've spent the course of the last 15 years doing Brooklyn/Manhattan nightlife, so if you'd like any suggestions for stuff to do, I can help you out.
Quick suggestions: Go to St. Marks near the lower east side of Manhattan, check out Kenka (AWESOME Japanese izakaya, open late) and Barcade across the street on the same block. If you're staying near Williamsburg though, I'd highly recommend going to Barcade Brooklyn over Barcade St. Marks. Video Games New York is a short walk from St. Marks, by the way. That place is completely overrated by tourists, it's overpriced as fuck but it has a lot of shit in there. I wouldn't spend a dime in there.
I prefer J&L Game in midtown Manhattan myself but I haven't been to J&L after they relocated there. They used to be in Chinatown and was my absolute go-to place to buy games/imports/accessories in the early/mid 2000's.
If you want a completely different NYC nightlife vibe, check out Astoria in Queens. Tons of bars and stuff open late at night and has a beer garden that's kind of a big deal.
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