Praise the Emperor, have we been waiting for this.
Seeing how there haven't been to many reviews so far, here's my go on the game so far.
Overall the game is pretty good even as a demo. Though it would be interesting if the various primarchs had different reactions to being TG'd. While many on here think its to do with Lorgar, I'd wager its probably Malchador and Emps (he [Mal] is referenced in canon, to wanting them to have been made female from the beginning) - well them or Tzeench.
Realistically I like what you've done with Lynn, she'd probably have the calmest reaction to being TG'd out of the primarchs, as the Lion was himself (subtly inferred to be) gay (though heavily in the closet), let alone getting wooed by the male MC. More masculine & infiriority complex harbouring primarchs such as Russ, Perturabo, Mortarian, Khan & Horus will be a lot trickier, though in the case of Russ it would be entertaining how his wolfgirl nature plays with his alpha-male tendancies (he'd be a wolfgirl tsundere/yandere [when Magnus gets involved]).
The easiest (in accepting their circumstances) Primarchs would likely be Sanguinius, Fulgrim (now he can have a chance in getting better hair than his father, and more oriphaces, depending upon her state of slaaneshi corruption), Magnus (whats a body, when your the second most powerful psyker in the galaxy - and now you can charm those old buggers into giving you their books) & Alpharius Omegon (imagine the possible of pranks they could pull off now
).
Primarchs that wouldn't really care (though having some uncomfortability) would likely be Guilliman (his/her mum would be overjoyed to finally have a daughter to dote over, let alone her over protective horde of 'sons'); Kurze (just miffed he gives his victims fairly insecure boners, while killing them), Dorn (magic pain glove still fits); Vulkan (now he can be the caring mother of his legion - but he has difficulty hugging his/her sons).
It would be pretty entertaining if certain primarchs could only be corrupted/redeemed after you've made waifus of others, like Ferrus after Fulgrim, and Horus after Sanguinius, due to how close their relationships were before the Heresy (and whom they likely had latent feelings, romantic or unromantic, for).
For the MC himself, I'm not to sure whether he's a Space Marine, a lost Primarch, a Guardsman, a Custodes, or a Thunder Warrior. Personally I'd prefer either a Guardsman (we can all guess who with Horus being involved) or a surviving Thunder warrior; mainly because 1. Perpetual/long livedness; 2. Balls of Admantine (in both cases); 3. I like the idea of the Thunder Warriors surviving the Unification wars, even if they're no longer in production like the Space Marines (also they are more immune to chaos/warp energy, and may have blanc abilities).
Overall good job so far, and while i'm strapped for cash, best of luck for the future, knowing how big the 40k community is (and how to be into 40k, your wallet has to be of a certain size) I'd say your picture costs should largely be covered by the second update.
Imperial_Briton