Border War is a set of fantasy skirmish rules.
Mimi and Toutou Go Forth is a set of simple naval rules for WWI naval battles on Lake Tanganyika. Obscure, to be sure, but intriguing.
Heroes of Victoria’s Empire is Bob Cordery’s
set of Colonial wargames rules specifically written to reflect the importance of heroic individuals (and villains!) during the expansion of the British Empire. The rules were written with the objective that they should be fun, and should enable a battle to be fought to a conclusion in no more than two hours using approximately 60 – 100 15mm-scale individually-based figures on a small tabletop (3¼ foot x 2½ foot/100 cm x 75 cm). It was also important that they should enable the story of the battle to unfold in front of the players.
Restless Natives is a set of free wargames rules for playing wargames in the colonial period. They’re intended for 15mm figures, and use a card-based movement and special events system.