How can you tell if your copy of a game is good or bad? The No-Intro project can answer that, and here's how it works.
Every game has a digital fingerprint called a "hash", and when two files have the same hash you know they're identical. The No-Intro project records the hashes of many videogames. Just compare your game's hash to the one in No-Intro and if they match, your copy's good!
To guarantee the best quality each NES game at Vimm's Lair is scanned nightly with the latest No-Intro data. Why nightly? No-Intro contributors aren't perfect, so over time corrections are made which changes the hash. Those changes are flagged for review, so if you see a flagged game and know where to find the new copy please lend a hand and upload it.