At its core Great Crusade: Ascendance asks the question, “what might have happened if the Horus Heresy had never occurred?”
More than that, it attempts to create the basic framework to build upon that premise and present the Space Marine Legions as they should have been, without the machinations of the Chaos Gods, their Primarch pawns, and other similar dupes. Instead, it envisages a universe where the Chaos Gods are victims of their own success and where the Legions flourish without the taint of their progenitors’ fall. It is not, however, a complete game system. Instead, it aims to give hobbyists a setting that they can explore in their own way, although there are some simple recommendations and starting precepts.
The setting is designed to allow hobbyists to use the modern plastic miniatures from the 2nd edition of Horus Heresy such as Space Marines in the iconic ‘Beakie’ style armour[1] and the sleeker, more modern war machines available as part of the range (such as Sicaran-pattern tanks, Javelin-pattern attack speeders, and other such vehicles). The aim is to create idealised forces leveraging the pinnacle of the war materiel available to the Legions at the beginning of the 31st Millennium (i.e., Late Crusade/Horus Heresy to Early Scouring).
In terms of aesthetic and looks, where the Horus Heresy and Warhammer 40,000 in general are notoriously ‘grimdark’ this project aims to present a cleaner, more hopeful vision of the future with a lot less grime (although battle damage, wear ‘n’ tear, and suchlike are left to the discretion of the individual hobbyist).
The project is inspired by the art of community stalwarts, such as @DesignJobber40k on Instagram, and his excellent work applying the original Epic paint schemes from the 80’s to the more modern iteration of Mk6 armour, especially where these schemes have later been used by Forgeworld to signify the ‘Pre-heresy’ look of the Legions. That being said, there will be some noticeable gaps and hobbyists are encouraged to interpret things as they see fit (the galaxy is a big place after all, and even within the Legions there were formations with non-standard colours and insignia).
In regard to rules, hobbyists have several options: The 1st edition of Horus Heresy, for instance, pairs reasonably well with codices from the 7th edition of Warhammer 40,000, or alternatively there are dedicated fan efforts, such as King Fluff’s notable books, which attempt to bring Crusade-era adversaries into the Horus Heresy setting. And finally, there is of course no reason why forces painted for Great Crusade: Ascendance cannot simply be fielded in normal games of Horus Heresy 2nd edition, ultimately the choice is yours…
[1] Although MK4 Maximus would also be acceptable as the logical predecessor to MK6 in this setting.