This is a very easy challenge. The first thing we see when we look at a hex dump of the file is the file signature:

4E 45 53 1A

Which is the plaintext NES followed by a MS-DOS end-of-file. This is the ROM file for a game to run on Nintendo NES.

Fire up your favorite emulator, and play through the first level.

In the second level, the layout of the level spells out the words “FLAG = 8 BIT RULES”.

Since challenge didn’t accept this a a flag, I had to message an admin via IRC to discover that the flag is actually 8bit_rulez