Literally Nothing. Not much to it.
The Nothing weapon is what takes up unused spaces in the weapon select screen. It can only be selected from the pause menu if the primary weapon is set to it or blocked, and even then, it still it does not do anything different. It will also take the place of a locked weapon put inside a Weapon Capsule when playing the level until the weapon is picked up.
Alternatively, it can be put to items designed around weapons, like Weapon Blocks, Weapon Capsules and Weapon Remover. For Weapon Blocks, it will render them utterly indestructible. Weapon Capsules set to it will fill the energy of the weapon currently equipped when the player character touches it. Weapon Removers set to it will block all the weapons when the player touches it.
It is possible to deal damage to enemies and bosses when "Nothing" is equipped while playing as Proto Man, since he can jump and use his Proto Shield to deflect enemy and boss projectiles back at them.
- Nothing's in-game description "You get nothing! You lose! Good day, sir!" is a quote from Willy Wonka & the Chocolate Factory (1971).
- Pressing the shoot button while "Nothing" is equipped will still activate behaviors for Robot Masters that react to the player's shoot button inputs, such as Metal Man, Crash Man, Toad Man, and Skull Man.