The ideas I am testing are a more board-game style of proceeding through the phases in order rather than setting up all orders at the start of each turn, using a "4x" style start as default and generating the whole map from scratch, simplified system types, using a new set of ship values (starting with Corvettes at Cost 2 / CP 8 ), new rules for cripple-able fighters, single squadron combat, and a couple more (like shipyards not having slipways, but instead granting a construction capacity cap of PROD x 2).
Here are the first 12 turns and some narration!

Initial forces include plenty of scouts for exploration. Both fleets chose a force to keep the peace in their home system and deter raids, but the Orks chose a huge Dreadnought which could be the flagship of the fleet they build up over the next few years. A bold risk!

Turn 1 sees successful exploration by the Orks, who are regretting their reduced income compared to the Imperials caused by the high upkeep of their Dreadnought. Hopefully it'll pay off and the Imperials will be more at risk of a raid.

The exploration luck seems to pass to the Imperials this turn, while both players make strategic purchases - a heavy Lunar cruiser as a flagship on the Imperial size, and more Savages to fill out their Scout maintenance group for the Orks. This is a bit quicker for the Orks, since their Savage DD costs less and builds faster than the Dauntless CL of the Imperials.

Skipping forward to turn 6, more exploration is fairly successful and both forces have finished some important construction projects, like the Lunar cruiser. Both sides also decided to save for expensive projects - a colony fleet to establish outposts on some of their newly discovered systems, and Productivity increases on their homeworlds to increase both their base income and their trade income.

By turn 12, the Imperial strategy is clearer - they want to beat the Orks to a tech increase, while the Orks are opting to build a maintenance group of Brute Ramship CTs to have a beats-all naval presence. The Imperials meant to build a second maintenance group of Dauntless CLs to have more Scouts available, but ended up needing those resources to increase the productivity of Majan's Rest and build their colony fleet and Lunar CA. This means they have three more Dauntless they can build without increasing their Maintenance, so you can bet they're going to do that. I note that I did the math wrong for the number of EP the Imperials will carry over to Turn 1 of Year 2, so I'll fix that - whoops.
Both have to choose going forward if they want to establish more Outposts, build a Colony fleet to transport Census to their existing outpost, or focus on exploration.
Comments? Ideas? Details you want posted? Would you prefer more "ingame" narrative? I'm not that familiar with the 40k universe of lore, but I could give that a shot.
I'll tweak which rules from Galaxies, clean up some of my math, and go to a different format for turn reports before starting the next year, so hit me with suggestions!