Hi,

I am a hobby game developer, and I am developing a HTML5 game engine for multiplayer usage. I am now at a point where I want to move forward on developing a small prototype of the game I am currently conceptualizing.

So far, I've been thinking about using 2D pixel art, as this means I can spend less time on asset development and more time on game systems, mechanics and environments.

I am, however, uncertain what effect 2D graphics have in terms of interest and sales of games. What is your experience as a game developer or gamer? Do you have any data/statistics to share on this?

I don't have any data, and I'd be surprised if anyone did. What effect could it possibly have? The answer is contained in the question: rest assured that the players you want are going to care about the game systems, mechanics and environment. And good, stylish 2D art is always appreciated.

It depends on the type of game.  2D graphics vs 3D graphics won't make a difference

Pixel art is a different story - it's an acquired taste and  polarising - some people love it and others won't touch it because it's consider dated, old-fashioned etc. 

Also note that pixel art doesn't scale well, despite popular belief, you need some settings on the user's side to override the default Windows graphics.  I saw that Unity has a special plugin / extension to solve that problem, but most other software I've played with doesn't have that feature and the pixel art becomes blurry when scaled up.

"I am, however, uncertain what effect 2D graphics have in terms of interest and sales of games. What is your experience as a game developer or gamer? Do you have any data/statistics to share on this?"

 I don't know if something like that exists... blockbusters triple As usually spend millions with the game and with marketing, and even though they can easlly flop due to the overall quality (Marvel Avengers and Fast and Furious as current examples, but we can get examples for everything of course) 

It depends much more with how much you'll spend with marketing... in the end, everything has its public (and after the marketing, people will judge its overall quality).

We usually try to make games we always wanted to play or an idea we think that would be great... but on all cases, we first do a game for ourselves with the style that most draws our attention, because if it is for you, you, at least, can assure its quality (So, how do you truly idealize this game? You first do think of it being in 3D?)... later, the people that have your same taste will get to your game and will turn into your public (with marketing too, of course, people have to know it exists).

2D games have the advantages of being easier to do for a single person or a small group and of running on every hardware possible... those games usually are the salvation of people with modest hardware that still want to play nowadays games.

Thanks for all of the answers. They're definitely putting my mind at ease on this subject. I did read an article about the future of 2D gaming from gamesindustry.biz, where the author interviews a number of game developers. They're all very positive on the future of 2D in general, and are seeing a revival of the medium. They did also discuss the value perception, which all besides one thought did not contribute negatively to the value of the game.

You can hardly find any real 2D games in the shelves anymore, except for entire collections of retro games as one product. Todays top notch "2D" games are pseudo 2D, the images are textures on some quad meshes facing the camera. This allows for many fx that are hard to achieve in real 2D, like antialiasing, blendmodes (esp. addition for sfx) rotate, scale, sub-pixel-placement, zoom, alpha, light, shadows, particle, fog, fragment shaders.... Therefor, 2D is fine when you use the latest technology, that is in effect 3D, resembling 2D. Real 2D, like we had 100 years ago, meant: masked sprites only, not even an alpha channel. You won't earn much respect when you challenge todays 2D games with original, real 2D. But the concept of 2D games, like sidescrollers, point'n'click, hexa tiles, topdown etc. is still well perceived, if the graphics are up to date and real eye candy. Above all that you need a theme that has an audience.