This game is the fifth entry in the GT series. The Gran Turismo Series is a long running line of simulation racing games, dating back to the PS1, each with its own evolutions. This year, its the new XP system, and a long line of new event types. Since this is a simulation racing game, there is more emphasis in skill than in other sub-genres. These games also strive for realism, meaning you will get a true to life experience. Also, this means you will need to erect new strategics, no worry that's what we are here for!
For the first time, GT5 has 16 player online multiplayer. Also, there is now a XP system. Every time you complete and/or win a race, you get XP. This is how you unlock new events, and ability to buy cars. This make car grinding less painful. Also, there is the Track Editor. This mode allows you to create tracks. There are multiple themes to choose from, and they get added to your tracks list. There are other additions, but these are the most important ones. In other words, there is nothing like them. Yes there is NASCAR, but in reality that is somewhat incomplete.
This game has two main modes. Arcade and Simulation. Arcade is the equivalent of a quick race mode, where you can quickly get into a race and practice, while Simulation is the meat of the game. This mode allows you to be in the fast life of a driver, in A-SPEC, or raise a driver to victory in B-SPEC(see more in the dedicated section). There is also two new modes this year, Course Maker, and Manual. Course Maker is where you can make your own tracks. Manual is essentially the help section in this game.
This is it for that. There is more of this in detail, in the table of contents, and under getting started. The cars, tracks and other things fall under the appendices. And the main A-SPEC and B-SPEC chain of events is under the walkthrough.