Nikujin

Nikujin is a PC Freeware Game made by japanese developer Ikiki in 2006 that became one of his most well known games. In it, you play as a naked ninja, who’s goal is to progress through a ninja fortress of increasing difficulty, utilising your ninja skills to ensure your survival.

This game contains examples of:
 * Action Bomb: The red ninja who'll run at you while screaming to explode in your face. You need to call his attention wisely so he'll take out iron doors.
 * Author Appeal: Nikujin wasn't the first of Ikiki's games featuring naked people killing each other stealthly, nor it was the last.
 * Barbie Doll Anatomy
 * Bonus Stage
 * Ceiling Cling
 * Check Point: Only the tutorial level features those.
 * Crowning Moment of Awesome: The ending.
 * Endless Game: The survival mode.
 * Full Frontal Assault: No, really, all the ninjas in this game are naked.
 * Goomba Springboard: Stabbing enemies in the head has this effect.
 * Highly-Visible Ninja
 * Instant Awesome, Just Add Ninja
 * Ninja: NAKED Ninjas!
 * Nintendo Hard: Definitely.
 * One-Hit Kill: The Goomba Springboard move mentioned above. But it only works if the enemy hasn't seen you.
 * Stealth Based Game
 * There Is No Kill Like Overkill: What Nikujin does to his enemies' boss at the end.
 * Trial and Error Gameplay: Make any mistake and even if you don't die, you'll probably have to kill yourself and start over.
 * Wall Jump