If you are looking for a laptop to last at least 5 - 6 hours when playing games, then there are no such laptop in existence.
If you mean at least 5 - 6 hours of average daily light usage, then it is possible to find such a laptop, but it can be difficult. Ultrabooks generally have good battery life in the range you are looking at, but they generally are not equipped with a powerful graphics chip. Gaming laptops tends to have about 4 hours of battery life, but many seems to be less than that. Also, the higher the screen resolution, the lower the battery life tends to be.
The Sager NP8230's battery life is rated a 2+ hours and that's not while gaming either.