Gimmick (noun)

1. A trick or device used to attract attention or increase appeal.
2. A feature or device that is added to something to make it more attractive or saleable.

Origin:

The word "gimmick" originated in the early 20th century, it is believed to be a variant of "gimcrack" which means a "cheap showy trinket.".

Examples:

1. The new car's fuel efficiency was a major gimmick to attract customers.
2. The magician's disappearing act was just a gimmick.
3. The restaurant's gimmick of having a live band perform while you dine seemed like a good idea, but it was too loud to have a conversation.
4. The company's new product was just a gimmick that offered no real value.
5. The store"s "buy one get one free" gimmick was a hit with shoppers.