Basic Impetus is the fast-play version of the Impetus set of wargames rules, published by Dadi & Piombo.
This is a set of rules designed for playing battles in the Ancient, Medieval, and Renaissance periods.
The rules are designed for fast play, using relatively small armies - you can fight a battle in 60-90 minutes using forces of 7-10 elements a side.
The game can be played using various scales of figures: 6mm, 10mm, 15mm, 20mm, and 25/28mm.
Figures are based in elements with frontages of 60mm, 80mm, or 120mm wide (depending on figure scale).
The rules and army lists for the game are free to download and are fully supported by Dadi & Piombo. There are currently army lists available for 34 different periods of history - anything from Ancient Egypt through Alexander the Great, the rise and fall of Rome, the Dark Ages, the Crusades, the various conflicts of Medieval Europe, and the wars of China, Korea, and Japan.