Necron's Keep by Dan Welch

Bluex the divine king of Surya has decreed for you to locate the Arch Mage Wizard Necron. Necron built an enchanted castle deep within an ancient forest to protect himself and his people. Esentially, you are being sent to investigate since no communication with the outside has occured for over twently years. Your master gave you a dragon skin tome from his own private library, and a magic bag of holding. The magic bag allows you to place an unlimited amount of things into it. As a magic user your primary ability is to cast spells. By collecting experience points, you may progress upwards in "level". Your odyssey pits you against the supernatural forces that oppose your efforts to reach deep within Necron's Keep. Read on, adventurer. Your quest awaits!