There’s an old D&D system that you’ve probably heard of.

It’s called THAC0, which stands for “To Hit Armor Class Zero.”

Whether you pronounce it thay-co or thack-oh, if you weren’t contemporaries, you probably heard about it in a less than favorable light.

The reason it became the butt of jokes was a combination of factors:

• It was a relatively simple concept explained in a convoluted manner. When THAC0 was moved into the AD&D Player’s Handbook and officially termed, the explanation was confusing enough that you could fairly read it backwards.
• On a more mechanical level, the “roll low” system was counterintuitive. Western society generally conditions us to believe that “more is better” and it’s mentally jarring to break from that trend.
• Finally, addition is also the most basic form of arithmetic, and works a little bit faster…