White Box: Fantastic Medieval Adventure Game is an update with new art and layout of the excellent Swords & Wizardry: Whitebox. This is not an official S&W publication. It is my own version with a few added ideas from various other OSR sources. But it is very similar and compatible with the game on which it is based.
From the introduction:
White Box is very easy to learn and play. The basic rules are simple and clear. As you create your character and read through the rules, you will see that there are several Alternate Rules described.