Like in most games, there is a title screen on which you simply press start. The main menu allows access to all the game modes. You can dive straight into the game, host (or join) a multiplayer match, forge your own level, view unlockables, adjust options, or view the masterminds behind this game.
If you select main game, the menu will change. New game starts a new game. Load game lets you continue from where you left off last. User data allows you to play your custom levels with a time limit. Tutorial gives you a rundown of your moves and allows demonstrations.
Multiplayer allows you to play with a friend (or foe) in four frantic game modes -Blitz is a race for the goal. Go through the exit as many times as possible. -Tag is a game where whoever is "it" must tag the other player. The player that is "it" will lose time. -Domination is a competition for the most switches. -Co-op is a mode where, instead of rivals, the two players are allies that team up to reach the goal. So long as either ninja reaches the goal, both players claim victory.
Level editor allows you to create your own levels (up to eight). To test your level, press SELECT. Keep in mind that even though testing your level has no time limit, playing it in main game does, so stock your level with some gold. Also, please make your level possible. "Even ninjas can show passion occasionally" (Excerpt from N+ instruction manual)
Unlockables allow you to pore over your accomplishments.
Options allow you to modify the game to your liking. For example, you can make the game appear like its Internet counterpart, with geometric graphics. You can also customize your ninja's color, allow for a blood-spatter when killed, etc.
Credits show the people responsible for making the game. Thank you, Atari!
Just as a side note, all the letters in the game are lowercase.