Britons

Britons: One Brain Cell Wargame Rules for Tribal Skirmishes in 1st Century Britain.

From the rules:

"These are rules for playing a wargame with toy soldiers. It is intended for several players - say 4 or more, but can be played with fewer."

"Players control heroes (and, of course, heroines), who in turn have contingents of fighters under them."

"The setting is the constant inter and intra-tribal conflict that characterised Celtic society in ancient times."

"These rules concentrate on the actions in a raid. Raids could involve anything from a few dozen to several hundred, and could involve considerable fighting."