Genocide relates to a race.
Ethnocide relates to an ethnic group.
Indigocide relates to both an indigenous people and their indigenous culture.
Indigocide relates to multi-culturalism and its emphasis on colonisation as opposed to integrationism.
Indigocide is not an action undertaken by the government aiming at a direct extermination of a race or an ethnic group eg the construction of death camps or gulags, but relates instead to the actions of a government via their social, political, cultural and immigration policies that cause the indigenous peoples and culture of a nation to be marginalised and eventually disappear.
The fact that the Cockney language form of London will vanish in less than 30 years is an example of Indigocide.