I've been playing around with the idea of taking
40k, burning the whole thing, and starting the rules over again for years, but recently sat down and actually finished writing it up. My revised version has a two-phase turn with alternating activations (based on Kill-Team),
USRs, and has culled a lot of the endless proliferation of constraints and unique special rules in favour of trying to standardize how and why the rules work.
Core rules:
https://docs.google.com/document/d/1zXHLmrG-Vgh9wlus4PGFjWckhf744xdnOMUMata-AkU/edit?usp=sharing
A selection of armies:
https://docs.google.com/spreadsheets/d/10HNFV8d_0RVT2Z3D9DmzUQlPWIrre8kOKb7sMmLaHHc/edit?usp=sharing
Status: Marines, Guard, Mechanicum,
CSM, Corsairs, Orks, Necrons, Tyranids, and Tau have a basic selection of units and statblocks with approximate points values.
Plans:
--Ongoing: Rebalance, fiddle, and adjust numbers.
--Phase 2: Extending existing forces to include heavier armour (up to Knight-sized baby superheavies), aircraft, and more specialized units. Creating a sub-faction structure.
--Phase 3: Extending forces to include Custodes, a general Militia/Gangs/Cults force, Inquisition, Ecclesiarchy/Sororitas, Daemons, Craftworlds, Dark Eldar definite. May add Squats, Kroot, Rogue Traders, and others depending on time.
--Phase 4: Defining a broader array of specialized alternate Detachments. Extending the scale of the game to allow for full-size superheavies (Baneblade and up).
FAQ:
Q: What happened to the Primaris Marines? A: I've attempted to reduce redundancy by interpreting Primaris models as resculpts of classic models rather than entirely new units with different statlines. The skimmers will be their own datasheets but the characters and the infantry are going to stay consolidated into the same datasheets as the normal non-Primaris units. If there's too much confusion as to what's supposed to represent what I will go back and write in modelling suggestions in the unit entries.
Q: Where's (unit X)/(army Y)? A: The spreadsheet at the moment has a representative sample of units rather than a comprehensive list of all datasheets. You'll notice that there's nothing bigger than T8 medium-heavy tanks (Russes, Doomsday Arks, Battlewaggons, and the like) and there are no Flyers, there will be when I'm done but there aren't for initial testing. Similarly I tried to set up a distribution of armies that gave me a good spread of stuff rather than representing everything right away, which is why the Eldar are Corsairs (they let me test a lot of Craftworld and Dark Eldar chassis and weapons without needing to go in depth about the Kabal/Coven/Cult distinctions or defining all the Aspects), there's no Inquisition (they're a mixture of Guard stuff and Marine stuff, I'd like to test the constituent elements independently first), and no Daemons/Custodes (both are going to be weird to write and don't have a lot of stuff that gets translated across armies).
Q: Where are Chapter Tactics? A: I dislike 8e's interpretation of the concept and am working on my own, but at this time it isn't complete or represented in the rules. Expect something more like 4e's Chapter Tactics (where the rules aren't specifically and explicitly linked to your background) in order to avoid making people paint their armies a colour they don't like to get the rules they like.
Q: I don't understand vehicle facings/the cover rules? A: I've been told they make sense when you see them on the table but I haven't explained them very well, will be drawing diagrams at some point.
Q: I don't understand the statline? A: Move is walk rate/run rate, DR is intended to bring back the idea of vehicle armour facings and is front/sides/rear (at the moment everything attacks into the facings they're actually in with ranged attacks and melee attacks hit the rear facing), and Save is armour/invulnerable. The rest should be self-explanatory.
Q: I noticed a typo... A: Good! Let me know and I'll see what I can do about it.
Q: I think I found a way to get a 2+ Invulnerable save? A: Crap. I thought I'd managed to not do that. Where is it? I need to nerf something.