Robert Boyd (from Zeboyd games) is having an interesting conversation on Twitter. I took the liberty to copy paste it here.

https://twitter.com/#!/werezompire


“In this day of connectivity, how do you make it so that players will be surprised playing your game and not find out before via previews?”
“ Which makes perfect sense. I guess my question is how do you get people excited for something without spoiling everything?”
“I guess the more accurate question is how do you get people excited for a game without revealing all your cool features beforehand?”
“I think a big reason why a lot of people don't complete games is because they feel like they've already seen everything before they finish.”
“So I think as game developers, we should try to add new elements and types of gameplay throughout the entire game.”
“For example, a turn-based RPG that later on has a few bigger scale Strategy/RPG style battles.”
“Nothing drastic like "FPS turns into platformer" but new elements that build on the game's core and add a strong new twist.”
“I'm not talking about something like Brutal Legend where people thought it would be Zelda and it turned out to be an Action/RTS.”
“More like the original Portal where at a key moment in the game, the game evolved in a surprising direction.”
“ Which is fine and good but there's a reason for all the PR stuff. You still want people to buy your game. :)”
“These days, most people are afraid to give story spoilers. But gameplay spoilers? Reviewers almost feel its their duty to spoil those.”

I tend to agree.

That must be the reason I don't complete even half of the games I start. I should stop reading Wikipedia.

I think the story or the rewards is what pushes people forward, but it's the gameplay that keeps them trying. Not telling your players what to expect generates zero buzz. The only way it could work is if you're already a well known or famous developer who always delivers good stuff. Only that amount of trust in your track record would get your players buying your product without caring what it is.

Some people like some kinds of genres and dislike others. To go into a game completely blindfolded regarding the gameplay doesn't seem so wise to me.

I agree quite a bit too. Skyward Sword for example, I wanted it for months and months and months, couldn't afford it and wasn't at home enough to have access to the console. I downright refused to watch any video, read any review or detail that featured the game in any amount. But, I knew it was going to be good, alone based on the concept and it's appearance at E3. It showed how important it was to have control without spoiling just how much control you'll be given to solve puzzles, navigate, and in combat.

It's the same thing I think with most games. Everything is starting to blend in where you have to spoil what your game is beforehand to actually stand out. But then surprises are hard to come by. The only way to do that then is to exploit those massive surprises by progressing with the simple, to making you wonder about what's possible. Example, Portal. What if you were trying to show this game off without spoiling it? My solution, a playground room as a demo. Let people experiment with throwing themselves around with portals, going across the room, interacting and changing it as you wish. It's not the most complex thing, but it allows people the chance to build interest in their own way.

What about shooter games? Actually, no, everyone knows what to expect, move along folks, it's about Nazi's or Russians or Taliban or Aliens. Pick two, game 1 is going to be like game 300 in almost every way unless you were Id Software before Xbox.