I like the presented solution in general, but making the army cost more as it grows bigger may represent the difficulties of controlling and communicating a large army in the real world, with all the bureaucracy, hierarchies and logistics. So maybe something like a +1% or +0.5% of overall unit maintenance cost for every unit a player owns, which would be easily visible in the UI? Gold is abundant in late game, while in early game +10% to unit maintenance wouldn't make much difference (20 Classical era units with +10% costs would make 40+4). And buildings maintenance costs much more than units in late game (at least currently).
Considering proposed flat numbers:
- Post-Renaissance scout line has units which in real world seem to be more of an elite and specifically trained forces (like Special Forces

), which require better equipment, constant training to be in shape, and the best men available. In the game, they have unique abilities compared to regular infantry. Besides, the player probably won't have a lot of them in the late game (I usually have 2 hyper-promoted scouts from the early game, and some new ones to pillage and attack enemy's rear). So, I think they should be in the yellow cost zone.
- Tanks were produced in crazy amounts during WW2 by all sides, and even after the war at least by the Soviets (Russia keeps waging the War in Ukraine by restoring the seemingly endless stockpiles of Soviet tanks). So I imagine there would be a lot of spare parts and qualified repairers, and the cost of maintenance wouldn't be much higher. Infantry already has a discount compared to tanks. But if my view is historically inaccurate, then I am fine with higher cost.
- Continuing with tanks, this one is more specific: German tanks were significantly more difficult to maintain, and Soviet ones were easier, so maybe add a cheaper maintenance to Order's unique T-34 tanks, or an overall cheaper maintenance for all tanks in the Tenet which gives +33% Production to Tanks? Western tanks still seem to be more technological than Soviet/Russian/Chinese, and produced in smaller quantities.
- Nuclear Sub is a costly thing, not everyone can build and properly maintain it. But if goal is continuity of cost with previous subs, then I am okay.
- And finally: Nuclear Bombs and Rockets, as far as I know, are extremely costly to maintain and to keep it actually functional. One of the reasons Ukraine gave up its NW to Russia is because it was financially unable to properly maintain it. So if you do not use it immediately, and keep it as a deterrence against possible aggression, you should pay a lot for it. It is a big difference if you have NW at the start of a nuclear war, as opposed to you having to build it after your most industrious cities (or even all of your cities if you're playing tall) were nuked. I think it should cost even more than Carriers, 20 for Bomb and 30 for Rocket.
Otherwise, I like the idea and proposed changes.
P.S.: Is Authority's Conscript promotion intended to be lost after unit upgrade? Because this incentivizes not upgrading units if using them as garrison for Imperialism's Policy.