Joseph Morschauser’s wargames are designed to be played on a square grid. The Frontier Wargames set is for colonial games.
De Bellis Indica is a DBA variant for simulation of warfare in India in the 18th and 19th centuries. The basic scale is 1 figure = 50 men and 40mm = 100 paces
Valley of Fire is a free campaign system for the Northwest Frontier. The authors write:
This is a fictional colonial campaign set in the Northwest Frontier during the late 1880s. A British fort is under siege and a relieving force has exactly one month to break the siege! The villages in the valley and mountain passes go into revolt, adding more and more foces to the siege and to block the British advance. The system features hidden movement, is of moderate complexity, and is designed to be run with or without a referee. The PDF contains rules, counters, a planning map, and log sheets.
Heroes of Victoria’s Empire is a set of free wargames rules for heroic actions in the colonial era.