Versatility of style in video games has expanded tremendously in the past decade. I'd say there are more styles found in games than in any other form of entertainment. With such dramatically different visual styles and the advanced technology that games now have I'm actually finding it a little disappointing at the implementation of these visual styles in games. Many of the times it's used to match some other successful style, or it's style for the sake of style.
When it comes to games it's gameplay is king and everything has to . As of now the most successful games use their visuals to help explain direct the player through spaces and indicate how to solve challenges or set the mood of the story. This is all good and well but should be expanded on to make room for making the visuals their selves interactive and tied even closer to the gameplay.
Hazard: The Journey of Life is a game that has a visual style that I can't really describe. It's visuals don't serve a purpose to anything other than being different. It's visuals are an attention grabber but has no depth or connection to the gameplay.
Team Fortess 2. Awesome art direction but while it's exaggerated shapes and style create it's own visual language for it's players to understand the gameplay, there are some aspects of the visuals that just don't go as far as others. Still a very successful visual style and should be something other games styles try to achieve.
Minecraft is an example where the visual style is based entirely off of the gameplay. The core mechanic is building with blocks. The art is all blocks and squares. The visuals tie their selves to the core experience of the game entirely. While it doesn't look to be anything better than programmer art, I still consider it to be an elegant approach for it's visual direction.