What If? An alternate ending to Horus Heresy.

[Tyzuris]

Assume that Corax, Manus and Vulkan manage to get info on how the other four reinforcing Legions have turned traitor as well, and they pull back from attack on Istvan. And assume that over the course of the HH and its resolution all the traitor Primarchs are killed off with all loyalist ones surviving.

And from there on two scenarios:

1. Emperor still gets wounded and winds up on Golden Throne.

2. The Emperor doesn't get wounded and is still left on the Golden Throne to fight off the Warp Daemons trying to attack Terra.

How will this affect things now that all loyalist Primarchs are alive and no traitor ones are left alive?

 

[ATP]

Assume that Corax, Manus and Vulkan manage to get info on how the other four reinforcing Legions have turned traitor as well, and they pull back from attack on Istvan. And assume that over the course of the HH and its resolution all the traitor Primarchs are killed off with all loyalist ones surviving.

And from there on two scenarios:

1. Emperor still gets wounded and winds up on Golden Throne.

2. The Emperor doesn't get wounded and is still left on the Golden Throne to fight off the Warp Daemons trying to attack Terra.

How will this affect things now that all loyalist Primarchs are alive and no traitor ones are left alive?

No Ecclesiarchy,no or weaker Inquisition/Primarch doing their job/,smarter Mechanicus.
All in all,in 40M there would be no Tau/sorry,they get killed here/ ,Tyranids would be partially stopped,Chaos weaker,but Necron,orks and Eldars as bad as in canon.