Heyo! ChapterAquila92 here! My local gaming group, in conjunction with some further interest within a regional Horus Heresy community whom most of the group members are a part of, has recently gotten into an unofficial 30k variant of BFG titled Battlefleet: Heresy (referred to here on in as BF30k). Pretty much what it says on the tin, it's Battlefleet action during the Horus Heresy. Building off of the core rules for BFG, BF30k's biggest difference from the vanilla game is that Loyalists and Traitors both have access to ships from the Imperial Navy and Chaos ranges (an amalgamation referred to as Armada Imperialis), with a few exceptions based on their canonical absence from the time period. Only Legion fleets (loyalist and traitor alike) may also take the usual BFG Space Marine ships, but they can also add Astartes crew to non-Astartes ships they take at +15pts per ship for improved boarding/counter-boarding capabilities and leadership. In addition, Legion-specific rules are also available for Legion fleets, as well as fabled Gloriana Battleships. Since the models are not being produced by GW or FW these days, we've been having to rely on Soul Forge Studio for STLs to print. Thus far they've been pretty good quality. As for myself, I've been collecting a Salamanders fleet that's currently got enough ships to play at 2000pts. At 1000pts, I'm typically running the following: Astartes Master of the Fleet - 100pts 1x Escort Squadron of 3 Firestorm Frigates each - 120pts 1x Escort Squadron of 4 Sword Frigates each - 140pts 2x Lunar Cruisers (all with Astartes crew) - 195pts per cruiser (290pts) 1x Eclipse Battlecruiser [FLAGSHIP] (with Astartes crew) - 230pts Total: 980pts At 2000pts, I'm able to field the following: Astartes Master of the Fleet - 100pts 2x Escort Squadrons of 3 Firestorm Frigates each - 120pts per squadron (240pts) 2x Escort Squadrons of 4 Sword Frigates each - 140pts per squadron (280pts) 3x Lunar Cruisers (all with Astartes crew) - 195pts per cruiser (585pts) 1x Dictator Cruiser (with Astartes crew) - 235pts 1x Dagon Grand Cruiser (with Astartes crew) - 245pts 1x Desolator Battleship [FLAGSHIP] (with Astartes crew) - 315pts Total: 2000pts Salamanders in BF30k have the Promethean Creed special rule, in which all vessels with Astartes crew have the effectiveness of their weapons, turrets and shields reduced to 75% when crippled instead of 50%, but may only grant the Astartes Crew upgrade to no more than 1 out of every 3 ships in the fleet (This is predominantly why I have so many Sword and Firestorm escorts in this collection). The fleet's flagship may also take melta torpedos for free.
I don't know about any projected re-release for BFG, to be honest. Insofar as this particular supplement is concerned, it's more or less created by fans for fans (specifically, the Remembrancer's Retreat).