Recca

Recca is a self-described "super hard shooting game" that's very modest in describing itself. It's also very impressive for being an NES game, but they don't mention that.

Disabled Intro
BrQn-O_zFRc The Game Genie code will enable an interesting intro sequence by holding Start before the animated "naxat soft" logo appears.

The intro shows the Sega logo appearing with its usual sound effect, then blowing up. Its replacement, a Nintendo logo, moves down the screen much like the Game Boy startup (complete with sound effect upon stopping). Both logos have the "e" replaced by a "?".

Interestingly, the "Game Boy" microgame in WarioWare, Inc.: Mega Microgame$! uses the same style of Nintendo logo in its mimic of the Game Boy startup, despite the border not actually being present on the real startup screen.

Change Time Attack Limit
Usually, Time Attack ends after five minutes or when you exceed the score limit of 10,000 points.

If you press Reset while holding Select, though, you can change the limit to anything from 9 points to 9,000,000 points. Of course, the mode will still end if you lose all of your lives or run out of time.

Sound Test
Choose "Normal Game" and hold Select before the screen fades out. When the Sound Test screen appears, one of three otherwise unused songs will play at random.

Level Select
Enter the Sound Test, then press and hold A + B. Now, pressing Start + Select will allow you to increase a hidden level counter from 1-12, including the second quest stages (starts from Level 4). Starting a new game will take you to the selected level number.