Some stuff:
AFAIK AHD will be on Steam.
Steam is not required for AHD, in fact none of our internally made games require Steam. CK2 comes closest with the boxed version needing Steam activation, but there is still a non-Steam downloadable version on GG.
If you bought V2 somewhere besides Steam I don't think you can buy AHD on Steam as it will tell you you need Base V2 to play it. Steam does have a feature which allows you to add non-Steam games to your Steam libary, but I have not tried doing this and then buying addons via Steam. It's possible that it might work, but I cannot promise that it will.
AFAIK AHD will be on Steam.
Steam is not required for AHD, in fact none of our internally made games require Steam. CK2 comes closest with the boxed version needing Steam activation, but there is still a non-Steam downloadable version on GG.
If you bought V2 somewhere besides Steam I don't think you can buy AHD on Steam as it will tell you you need Base V2 to play it. Steam does have a feature which allows you to add non-Steam games to your Steam libary, but I have not tried doing this and then buying addons via Steam. It's possible that it might work, but I cannot promise that it will.