So just about every database of NES games, including this one, mentions an unreleased NES game called "Monster Masher" from Sofel.

The only source for this title is the old Grand Nestral Station list of unreleased game magazine coverage, and on that list, the only source is page 124 of Game Player's Strategy Guide to Nintendo Games vol 3 #4.

I'm looking at that page right now, and it looks like the old list had a typo: the game is clearly listed here as Monster MASTER, not Masher. Just a heads up in case you wanna update the database.

Edited. Thanks for the heads up.