The first of Creative Assembly's Total War spin-offs has been announced.

A Total War Saga: Thrones of Britannia is set It is 878 AD, following the Viking Invasion of Britain.

The Norse warlords are firmly established, but the ambitious kings of England, Ireland, Scotland and Wales have aspirations of their own – not least the great King Alfred of Wessex.

Britannia is a furnace of possibilities from which the template for modern Britain will be forged, said publisher Sega. It promises "the most detailed Total War campaign map ever made".

“Our aim with Total War Sagas is to explore key flashpoints at distinct places and times in history,” said series director Mike Simpson.

“Unlike our era-spanning titles, we’re putting defined geographical areas under the microscope, building super-detailed campaign maps with a strong cultural focus and flavour that players can dive into. This will complement our broader-scope titles perfectly.”

A Total War Saga: Thrones of Britannia will be available for PC in 2018.