Total War: Warhammer 40k is aiming to be the most complex and most accessible game Creative Assembly has ever made - here's how the devs managed both

The Total War: Warhammer 40,000 team at Creative Assembly has an interesting challenge on its hands. How do you create a game that lives up to the series' reputation as a deep tactical adventure while building a strong enough on-ramp for those new to the Total War series and to Warhammer as a whole?