T1 pgens aren't essential for T2 arty, it's a 4% reload discount which ends up being a 1.19x effectiveness for fully capped arty, coming to a profit of only 62 mass which is a negligible 2.8% of the total 2200 mass cost of the setup (unitdb).
This marginal adjacency is eclipsed by the idea that sparkies shouldn't build any eco structures so that there is no chance of them not being a combat unit.

As Deribus mentioned, I think reducing the size without changing the stats would make it too powerful in firebases, since you can basically stack 4+ instead of 3 shields to defend a T2 PD and they are high HP and low cost compared to UEF/Cybran.

Here's the overlap possible for a PD with the current shields:

I don't think being unable to upgrade the shield is a huge drawback, it just requires you to ctrl-k the shield and reclaim the small wreck before building the very cheap T3 shield. It requires some APM but definitely isn't impossible if you're defending something important that requires your attention with shields.

For the size complaint, I'm not sure what you want to shield. It can shield adjacent structures pretty well. Not entirely but almost everything:

For this pgen specific case I'd rather opt for a tiny increase in shield size instead of making the structure smaller.

I've been testing your size idea with the "Create entities" dialog (its in the hotkeys, you use the hotkey while a unit is selected and you can change its blueprint values. Spawn a new copy of the unit to make sure you get all the changes. Requires cheats):
4x4 size is just way too OP, since you get ~8 overlapping shields instead of 3:

5x5 size is enough to cover a pgen but its still a small shield so its not reaching towards diagonals:

It also still increases the coverage from 3 to 4-6 shields:

Decreasing the size even by 1 seems to bring more problems than solutions.

All in all, I understand why you dislike the shield but I think its strengths in HP and cost make it above average for firebases and protecting most directly adjacent things like T3 shields, pgens, factories, or engineers. The T3 shield is also very strong because it's super cheap and the 2nd most powerful, while giving sufficient radius imo: I've seen Aeon T3 shields easily protect air grids, artillery, or game enders from artillery barrages when a sufficient number are built (and number of shields is the most mass-efficient way of defending, so having a cheap shield helps a huge amount - natural regen is nearly worthless while recharge from 0 is extremely strong).

SMD missing and having to fire a second time is unacceptable. In that game the SMD firing twice actually lost the game.

I have published the SACU Rebalance mod. Afaik there are no bugs and its very playable: the balance is theoretical number crunching with very light T3/T4 land/navy combat testing, and all the game/visual design is implemented at a basic level (so you can look in UI for stats). Please host it/play it/sandbox it.

There's a github page with the working environment and commit history: https://github.com/lL1l1/SACU-Balance-Mod/tree/main

From the github:

FAF SACU Rebalance

This is a mod for Forged Alliance Forever.

Implements changes for the SACU rebalance proposed by balance team: cheaper SACUs, stronger adjacency/gateways, new army support enhancements.
Rambo SACUs are independently reworked with new weapons and upgrades to fill gaps in faction rosters.

General Changes

• Cheaper SACUs: Buildtime and energy costs are significantly reduced across the board.
  • RAS is more energy expensive due to decreased base SACU mass cost. RAS also increases death volatility of SACUs.
  • Weaker base SACUs: Unupgraded SACUs have less HP and/or DPS.
• Stronger gateways: Gateways consume 32-44 mass/s building SACU and have 160 buildpower, while costing 2550 mass, down from 3000.
• Stronger adjacency: Mass fab and pgen adjacency for gateways is un-nerfed and made equivalent to land factory adjacency.
• Engineering upgrade buff: Engineering upgrades are made much cheaper, especially on buildpower and energy, so that they can come close to engineering stations in power.

Faction specific changes (Rambos and support enhancements)

• UEF SACUs are highly armored with good firepower. They have powerful support enhancements and combat enhancements designed to engage T4 units.
  

• Cybran SACUs are lightly armoured and slow, but are highly upgradeable with enhancements designed to engage enemy T3, SACU, naval, or air units.
  

• Aeon SACUs are agile and have a powerful sensor suite (to counter underwater cloak) but are lightly armored. They have cheap combat enhancements designed to engage enemy T3 units.
  Aeon SACU nano is removed since nano does not fit the faction.
  

• Seraphim SACUs are highly armored with increased Regeneration rate but reduced firepower without combat enhancements. They have unique utility/support enhancements and powerful combat enhancements designed to engage enemy T3 units.
  Seraphim SACU shield is removed since personal shields do not fit the faction.
  

Fix here: https://github.com/FAForever/fa/pull/6884

This is a repost of a post made by @Jip on Discord:

It goes without saying that when an ACU is destroyed that it should explode. This discussion is not about the 'typical' way that an ACU ends up exploding. Instead, this discussion about what should happen when a player disconnects. There's some interest of adjusting this behavior, see for example:

• https://feedback.userreport.com/354e2fbd-fdb7-4282-ae57-df75bf625431/#idea/448833

And with thanks to @Nomander we now have a technical solution:

• https://github.com/FAForever/fa/pull/5971

We just have to enable it. At the moment it is disabled. We can make the behavior work like any of the other share conditions. And we can also introduce a new behavior: the ACU recalls individually.

The question that remains is how this feature should work in practice. A few relevant facts:

• A) It is difficult, if not impossible to determine whether a player left the game on purpose or because of technical reasons. We'll refer to this as the player 'leaving' regardless of what the cause is.
• B) It is possible to make it configurable, in the same way that the victory conditions and the share conditions are configurable.

And the primary questions for this topic?

• 1. Should we adjust the behavior of the ACU when a player leaves the game?
• 2. Should we make the behavior customizable (through the lobby options)?
• 3. The new (individual) recall behavior, how should that work exactly? Are there conditions, and if so - what are they?

I'd like to add some more details based on what's possible with the current implementation too:

• Aside from recalling the ACU individually, we can share the ACU for a limited time or permanently.
• The share condition for units can be changed based on if a player disconnects, and whatever anti-abuse measures are used (ex: use fullshare for disconnects unless we detect abuse, then use no-share just like for normal deaths).
  • Some ideas for anti-abuse measures are checking current ACU HP, if the ACU was damaged recently, or letting the ACU live (and possibly sharing it) and calling it abuse if it dies too quickly.

Second Iteration of Partial SACU Rebalance

The second iteration of SACU changes is now live on FAF Beta Balance.

Please make sure to host FAF Beta Balance, since the changes are not on FAF Develop.

The complete changes can be found on the changelog website.

Previous discussions about the first iteration can be found in the "experimental changes" posts on the forum and on Discord.

Iteration Changes

This iteration tries to prevent SACU rushes while making them a little more efficient lategame, and addresses Seraphim overcharge and UEF bubble shield. We encourage everyone to play with these changes and provide feedback.

All the changes specific to this iteration can be found in this commit history.

Early SACUs

Early SACUs were very powerful because you could only fight them with T3 units, and any failure would result in the SACU regenerating all damage, reclaiming wrecks instantly, and securing the area with structures. To prevent this:

• Significantly increased energy cost of survivability upgrades.
• Slightly increased energy cost of combatant SACUs
• Removed ACU priority from SACUs
• Reduce buildpower of SACUs by 25%, except for engineer presets and UEF. UEF keeps their buildpower because their engineer preset's drone can be shot down by AA, they have a weak pushing T4, and it promotes using their unique Ravagers.

Lategame SACUs

We do want SACUs to be good lategame, especially to stabilize lategame mass donations or air losses, which are factors that make players hesitant to attack and overall idle the game.

• Mass cost reduction for high-tier survivability upgrades (Cybran cloak, Aeon 2nd shield, UEF shield, UEF bubble, Sera shield)

Other

• Increase cost of Seraphim's overcharge upgrade to reduce its snowball potential. It's pretty much an upgrade over the ACU, and can replace the ACU's energy consumption, so the first OC SACU requires increased costs.
• UEF bubble shield receives a small buff to shield recharge time.

Future Changes

Future changes will be tracked in this pull request. When they are made, they will be deployed to FAF Beta Balance with a similar announcement here.

Maudlin is correct that assistance costs vary by shield, since it is based off of regen rate, repair cost, and RegenAssistMult.
Documentation on github repo:

--- How much buildpower is required to provide 1x of the shield's regen rate.
--- The cost of assisting a shield is repairCostRate / RegenAssistMult,
--- where repairCostRate is determined by Unit:UpdateConsumptionValues
---@field RegenAssistMult? number

These are the buildpower and mass efficiencies considering that repair cost is 0.75x the unit cost and RegenAssistMult is 60 for all shields.

Considering that defending a T3 Aeon artillery costs at least 165 mass/s, and a Mavor at least 550 mass/s, it is well worth economically to spam out multiple shields (they cost around 3.4k mass each) instead of assisting one, although it is riskier because the enemy can retarget the artillery, let all your shields get up, and then come down all together in the next few artillery shots as the overspill and splash damage take effect. Good for game enders that you need to protect at all costs but also need income to build.

2 Aeon T3 artillery one shot a shield and it is impossible to assist to prevent that currently.

Assisting works at full speed if you're stalling but that's a hard to fix engine bug/performance heavy Lua fix.

[Does assisting] speed up getting a collapsed shield back up?

No it does not. That is determined by the shield recharge time which will be added to the UI soon.

Aeon used to have t2 shields that couldn't be upgraded (unless my memory fails me) but that was patched as a balance decision.

The balance team does approve of letting them be upgradeable but there is simply no animation for doing so.

Good post. If you want you can take a look at/contribute to 4z0t's rings for all mod, it's set up to display range rings on top of units and currently there's no capture preview iirc.

As for interrupt pathfinding, it can get a bit out of the original scope with certain commands (attack move causing long range reclaim, load into transport from long range, capture from long range). We already filter the order to engineers only, but we could go further and filter by command type too, so it only works on what we want for good gameplay. Alternatively we should implement interrupt on assist/capture/auto ranged reclaim into the game going by the (poorly enforced) policy of integrating important mods into the game.

The cost of the TML isn't just 800 mass:

• mass cost: TML (800 mass) + missile (250) + some way to kill tmd, let's say 4 (easily countered) T1 bombers (360) = 1410 mass (unitdb) which affords 5 TMD.
• You need to get an extremely valuable central map position to be able to force out 6 TMD per enemy base. You then have to get T2 engineers to that position. Taking all that time + having to get the engis there (early HQ instead of eco) gets your opponent a T2 mex.
• You also have to build a TML instead of a T2 mex which gives your opponent extra mass to build TMD while you load the TML.

It's cool but clearly too powerful if you look at the unit mass costs (8k mass carrier coming with a free 10 * (1750+1500+195+1650) mass of units + no massive aircraft energy cost). I would turn down the initial numbers even if not aiming for a well-balanced, modded game.

@Nuggets Do you think there's some generic or simple instructions/skills that you could share?

@Nuggets You're right, I found a different private message where he said it more explicitly.

Yeah it's quite bad to get a bunch of cards and then ruin your entire game because you got too many mass production buffs.

It might be interesting to consider a different scaling for example multiplicative because the flat % decreases are very strong at low amounts. Like 200+30% mass brings you from 60->70% energy or -25% of your current energy. Same for build cost, although build cost is a positive trait so that's more fun to minimize (and it doesn't decrease buildtime anyway).

I actually noticed that build cost has a minimum limit, but it isn't specified anywhere in the UI or cards. In addition to that, build cost reducing cards should be removed from the pool when the limit is reached.

It's probably extremely difficult as a UI mod if your mod embeds all the strings inside its UI elements' code. The proper way to make it work is to use the LOC function for all relevant strings and prepend each string with <LOC keyName> . After that you don't have to do anything yourself, the modders can add localization to RoguelikeUiLocalizationMod/hook/loc/ru/strings_db.lua

@Deribus air scouts, t2 radar, spy planes, and t3 radar replace land scouts past at most early t2. Sure they're cheap but mixing them causes pathing issues and gives you a less dense formation, so that's why you get rid of them eventually.

I noticed a while back that resource production buffs aren't applied to RAS SACU.

• turn off energy and mass throttle in the options. Idk if mass throttle even works for the current ecomanager version.
• eco ui tools provides an alternative overlay
• ecomanagercbt has less agressive energy throttling and removes mass throttling
• don't energy stall

@seraphim-noob may be interested in that for his WIP rust client

Notably, there isn't a single AddSearchPath log line referencing the Mods directory anywhere in the game log — only the base gamedata (c:\programdata\faforever\gamedata*) and Steam install directory (f:\steamlibrary...) get mounted.

It seems like the game's file system isn't mounting your mod folder.
Check "C:\ProgramData\FAForever\fa_path.lua" to see that custom_vault_path is correctly set.
ProgramData\FAForever\bin\init.lua uses that value to determine what folder to mount for your maps/mods. The only way that could be broken is if you set a different init file in the client's launch args (unlikely that you did that).