A gimmick is something that tricks someone. It also means a clever plot or strategy. My dictionary gives the following example sentence: The contest was a gimmick to get people to sign up for their mailing list. This sentence means that people thought they were being part of a contest and were entering their email address to be in it, but in reality it was a scam / trick. The person who released this contest was only interested in gathering people's email addresses so they could then start sending out advertisements to these people. Gimmicky is the adjective form of gimmick. Here are some example sentences: 1. Requiring people to sign up for our mailing list to play our online game is so gimmicky. 2. You think you are getting a deal when you sign up for that credit card because they are giving you $35 for signing up but in reality, it is so gimmicky. Why? Because the interest rate is so high and they know a lot of people will fall into the trap of making purchases on the card without the means to pay it off in it.

Think of 虚有其表 显得很棒/很牛，但是要骗你，也没有用！