There were quite a few games that were announced for the NES that never did hit the shelves. This was due to many different reasons the most common being the game was not finished in time, it was not good enough or the developer/publisher went bust before it's release.

TITLE PUBLISHER ANNOUNCED

A Boy & His Blob 2

 Absolute Ent. Yes View

Ace Harding : Lost in Las Vegus

 Kemco Yes View

Airball

 Tengen Yes View

Alien Vs Predator

 Activision Yes View

Arcadia VI

 Software House No View
Basho Bazook Jaleco Yes View

Battlefields of Napoleon

 Broderbund Yes View
Beyond Shadowgate Kemco Yes View
Bio Force Ape Seta Yes View
Black Tiger Capcom Yes View
Buzz & Walldog Innovation Yes View
Californian Raisins Capcom Yes View
Chase HQ Taito Yes View

Crossbow

 American Video Ent. Yes View

Cue Stick

 American Video Ent. No View

Defectors

 Equilbrium No View

Dr. Franken

 Elite Yes View

Drac's Night Out

Parker Brothers No View

Earthbound

 Nintendo Yes View

Escape from Atlantis

Color Dreams Yes View

Exerion 2

 Jaleco No View

Free Fall

 Color Dreams No View
Happily Ever After Sofel Yes View
Happy Camper Color Dreams Yes View

Hard Drivin'

 Tengen Yes View

Hellraiser

 Color Dreams Yes View

Hero Quest

 Elite No View
Hit The Ice Taito Yes View

Inspector Gadget

 Hudson Soft Yes View

Licence To Kill

 Tengen Yes View

Lord of The Rings

 Interplay Yes View

Magic Sword

 Capcom Yes View

Mike Tyson's Intergalactic Power Punch

 ASC Yes View

Noah's Ark

 Matchbox Yes View

Police Academy

 Tengen Yes View

Pyramids of Ra

 Matchbox No View

Pyross

 American Sammy Yes View

Robocop Vs Terminator

Interplay No View

Street Fighter 2

Capcom Yes View

Sunman

 Sunsoft No View

Super Pitfall 2

 Activision Yes View

Squashed

 Jaleco Yes View
The Flash THQ Yes View

Thomas The Tank Engine

 THQ Yes View

Time Diver : Eon Man

 Taito Yes View

Xybots

 Tengen Yes View