Bill Molyneaux offers a set of free wargames rules for fighting the Zulu war.
Sand Pebbles Boxer Rebellion Edition is a set of free wargames rules from Bill Molyneaux.
Richard Bradley offers a set of Colonial Skirmish Rules.
De Bellis Indica is a DBA variant for warfare in India in the 18th and 19th Centuries.
Hordes of the Empire is a set of free wargames rules for playing 19 century colonial battles. It’s a variant of Hordes of the Things (HotT), which itself is a variant of DBA.