I recently shared some thoughts in this post on the Schell Games blog about the basics of creating characters for games, and some differences between character art in high res console games versus lower res online games. This was meant for folks who are unfamiliar with 3D graphics or game creation. I also copied the main part of the post below as well! Hope it's useful!
In the video game industry, 3D characters are sculpted in the computer on digital clay with very similar techniques used to sculpt physical clay. This digital clay is made up of many geometric triangles. Each triangle is made of three points in 3D space. When you connect these points with edges, you create a triangle. With this in mind, more triangles allow for more detailed characters on screen. In addition, textures are painted on top of these triangles to create believable materials like skin, hair, fabric and more. The characters you see on screen are the result of these many triangles combined with painted textures!
Now that you understand how characters in video games are made, you should also know that the hardware on which a character appears also influences how it is created. Many PlayStationⓇ or Xbox games in the first person shooter and action adventure categories use characters with 40,000 triangles or more, combined with highly detailed textures, since these platforms can dedicate memory more efficiently. If you and I both buy a Playstation, we have the same hardware on which to play the game. Since our hardware is the same, our characters will be shown in the same manner regardless of where we play.
In contrast, online streaming games with simultaneous players like Diablo, DOTA, Torchlight, and League of Legends are dependent on varying PC hardware resources. You may not have the same computer as I do! So when millions of people around the world with different computers are playing the same game online, the characters still need to look the same regardless of the hardware the player is using. In addition, large online multiplayer games like these usually showcase many characters on screen at the same time, and therefore, require lower triangle budgets with smaller textures to still run efficiently. It is the character artist's job to ensure that players still enjoy interacting with a smaller, less detailed character competing heavily for screen space.
As an example of these differences, more triangles allow the character to bend more believably at his joints when animated. In contrast, fewer triangles force the artist to be more creative when placing each triangle edge to achieve the best bending possible at the joint. Check out the images below for an illustration. These illustrations show the leg of the wild dog from the previous image.