Arctic

Sound Test
Actually, not so secret, a sound test can be accessed by pressing the B button on the title screen.

Unused Graphics
The game have total 5 x 4Kb full CHR data banks in the ROM. The fourth one never used, since it's actually an early prototype version of the main game's CHR data bank. The difference can be seen with unaided eye: different starting point graphics, arrows graphics, old uncleaned route tracks, different switch points, some routes hasn't graphics at all yet, etc. If you like to see how it look inside the game, use the Game Genie code.