As a gamer of many years, I've noticed a very common trend: Trailers for games that do not include gameplay. Oftentimes video game producers will throw up a few cinematic trailers, talk very little about a game, and then release it with so much baseless hype that people are confused as to what the game even is.
One example of this was Brink. It was from the developers of Enemy Territory: Quake Wars, which led a lot of people to believe early on that it would be a class-based multiplayer shooter. Which, by the way, it ended up being. It marketed itself as a class-based shooter with parkour elements, with emergent gameplay that was meant to be very new and unique. Which, for the most part, it had. The problem was, there was almost no gameplay footage until around a month before release, and many people had a LOT of misconceptions about the game. People believed it would be on a large scale, or that it was a Call of Duty knockoff, or that it would have a perk system that was specific to each class. A few of these things were partially true, but fewer were accurate, and even fewer than that were specifically addressed by the company in interviews. Part of this was a combination of journalists asking vague questions, and part of it was Bethesda and Splash Damage giving vague answers. 
Many games strive by hiding their weaknesses under graphics and cinematics, and oftentimes "gameplay footage" from a game is a glorified term for an in-engine cutscene. We see many titles that are hyped up beyond belief via promises given by developers and publishers, and much of the content funneled to the media resources are heavily filtered to look good, focusing on a gameplay element that may not even be executed very well outside of the given example. Trailers have become mainstay in the game industry, which is surprising considering how many video game websites there are out there to be given a chance to take a good look at the games and tell the world what they're like. Unfortunately, much of this opportunity is wasted on polar reviews or opinions that do not go into detail on any qualifying factors of a game, and instead just say things akin to "well, I really liked the shooting aspects, and the singleplayer was good", without actually elaborating on why, or which facets of the gameplay elements interested them.
There are billions of gamers worldwide, each with very particular tastes, and each group being a very particular market, yet most are categorized strictly by system and genre. Terms like "RPG", "Shooter", and "Puzzler" rarely have as much direct meaning as they used to, as many companies bend genre conventions to extreme degrees to define themselves as a unique product. There are still old-school developers who strive to refine the specific gameplay experiences they remember from classic games, and new indie developers that want to create unique experiences that draw upon nostalgia and enjoyment of those classics, but they are few and far between, as gaming slides into the realm of artistic design.
So, what does that mean for the common peruser of electronic interactive media? Well, you're not as informed as you should be. Many people go into a game with high expectations, after doing a huge amount of research via various sites, and sit down to a game on day one to find that the experience is nothing like what they expected, and it becomes a frustrating experience rather than an enjoyable one. There is a distinct problem when the marketing department of a game completely runs what goes out of the company's door as far as information. It is getting into borderline bad business when a company just plain avoids any direct information about a product other than taglines and bullet points.
When a company is asked what a game is, should they answer? Or are they protected by some magical veil of un-truth, that suddenly makes them non-liable when they bend the truth to sell their game? It’s hard to tell. But you can learn not to buy into the hype, and learn to do your research a little bit before you buy into a high-grossing game that you may or may not like. Every consumer should do their best to figure out if something is right for them, otherwise crappy games get put on a pedestal based on their unusually high sales figures. And then development time better spent on better games is put into a sequel. Noone wants that.