Ultimately the answer to this is tied in to exactly how complex the economic system is in the first place, I can't think of addressing one without covering the other, so apologies in advance if I ramble on.
Questions:
1: What does a unit "cost"?
2: What makes designing a unit worthwhile? What about the design process makes the unit different?
Disclaimer: All numbers used are made up, game terms used equally so, just for points of reference.
1: Costs and economy.
For creation, the first method is that the unit needs some notional investment of "production"; presence of the necessary materials; somewhere to build it and presul ymably a city building enabling this production. This is the Civilization method - These only need to be present, gold can be used to "hurry along" progress, and it's all very stuck in game logic as to why a city constructs only one thing at a time but can apparently do so at the speed of light, but runs out at the speed of light too. It's very hands-off and stylised.
The second method is the Warcraft method. You have a building to build with, you send your peons over to gather the resource from everywhere, and you spend those particular amounts on construction. A time-frame determined by the unit involved is your "training" time. This is a naturally more involved method, bossing around the minor day-to-day activities of your peasants. If a resource is cut off, you have reserves stored in some magical ether. It's not inherently very compatible with a turn based strategy without a little work.
To cover this question, an ideal compromise I believe would be thus:
A) Resources are gathered and spent, not binary states.
In reality, large-scale centralised industrial ventures are a rather new thing. Coal mines didn't happen on some single isolated locale, small mines dotted the mountainside.
Each standard resource has a numerical amount, gathered by your cities and gatherers at a steady, but low, rate per turn. Have a city in the mountains? Each mountain tile has small mines maintained by your populace. Grasslands have farmlands, vital for producing the necessary foodstuffs for a large city. The rarer a material, the less each square would yield, and you must have the appropriate technical capability (and potentially building) to harvest each material. Remember MoM's surveyor? I do. A surveyor could say what a city in each area would gather based on its known surrounding tiles.
Standard type resource nodes (adamantium would be standard, magic honey bees not) produce a larger amount of a selected resource - No special gathering item is necessary on the tile itself, it simply needs to be within range of the city.
If you don't want a city in every spot, gathering points (either universally appropriate trading posts, or possibly ones that give bonuses to specific resources, such as mines, sawmills and farms) can be built cheaply and easily but cover a smaller area (if a city covers three squares each direction, then a trading post covers 1 square).
For non-standard resources, a specific tile-based improvement is required to harness it - Honey in a honey tree? Beekeeping structure. Pack of minidragons? Either a hunting lodge (to harvest those skins), or a training lodge (to train up riding dragons). Non-standard resources should be big, flashy, and provide a potentially massive change to a unit equipped with it. Likewise, any choice between two optional uses of a resource should involve a significant trade-off either way.
This trade-off might even be possible for standard resource nodes. Grove of trees - Great source of mystical yew with a sawmill, or create a druid's grove instead, and let the tree huggers generate mana and unusual unit options? Farm for food and cottons, or ranch to supplement your horse cavalry?
This method of cost is a little bit of A, a little bit of B. You might run an entire empire on iron without a single iron node if you have enough mountains, but it's unlikely you'll gather enough Adamantium from that same empire to make up a single unit of it per turn (and it takes five units to make a single adamantium armoured soldier). With unique materials, you will never be able to make a dragonknight without a pack of dragons, or taking the time to tame at least a few before hunting the rest, nor will simply having the resource be a white card for unlimitted production. If you want an army of tanks, you will need to conquer as many oilfields as possible, not just the one.
The maximum storage available for each resource depends on the number of appropriate buildings in each city for storing such materials. Here lies another aspect of choice B: You can probably magic up some materials, buy some off your neighbour, barter from your neighbour, disband a unit to reclaim the equipment, or flat out steal it (or have your intrepid heroes help. Kill an adamantium golem? Free adamantium!).
There should be two types of universal resources - Gold (or equivalent), and Mana. Gold can be used most easily for trade, whilst with the right spell, minerals can be called forth from the earth, converted from type to type, and generally the laws' of physics should be magically shafted up the large hadron collider. Since it's likely that there is private ownership, surplus can be automatically sold "privately". Likewise, a deficit can be made up - if your nation has a resource available at all - by "buying" it from privately owned sources at a premium.
For conquest, conquering trading posts/mines would both damage their ability to gather as well as steal a proportion of resources relative to the trading post's area production. These same areas destroyed by NPC monsters destroys a portion of the resources and loots the rest, converting the post into something else. A farm slaughtered by undead might become a haunted farm, filled with manic attack scarecrows and children of the corn. A trading post raided by bandits might become a bandit encampment, serving to send more bandits into the surrounding areas. A mine invaded by kobolds and vulkans is an abandoned mine... All great places to go for adventures, both to recover the lost wealth and to seek treasure, fame and fortune. Possibilities are myriad.
Caravans can remain in this system, whenever a trading post exceeds a certain number of units of a resource, it creates a self-automated, self-defending caravan (for free, including a free, if small, mundane defence force). These caravans move directly to the closest town. Multiple caravans group together for defence. The minimum number of caravans to make a trip worthwhile can be set either globally or individually - A trading post next to a far-flung resource that would take five turns to reach a town would need a larger - and therefore better defended - group than a caravan that takes a single turn and so goes as soon as resources are available.
Finally, this trickle of resources can be a setting or a feature of a region/tile itself - bountiful terrain with a high level of passive acquisition, a barren land with little to none, or mineral-rich/food-rich... This would offer a highly variable system with comparitively small amounts of work on the individual settings.
B: Materials are useful.
The wide-swept assumption seems to be that materials become obsolete, like in Civilisation, the higher you go.
This seems a little strange, especially given the fantasy setting, and I truly hope that this hasn't gone in that direction. Every resource should be useful, and for more than providing some generic +1 bonus. Here's a few examples.
Iron: A highly common metal, untreated iron is fairly brittle, heavy, and generally outclassed by steel. Why use it? Iron is lethal to fey creatures. It protects against faerie magic, it harms them greatly, and it's better than bronze.
Silver: A softer metal, usually poor when it comes to equipment. Why use it? Silver is highly enchantable and great against lycanthropes. It's also rather valuable to private citizens in the form of silver jewellery, making it a good source of currency when its more esoteric uses aren't required.
Steel: Slightly softer than untreated item, but less brittle, steel, when it has been researched, comes from the same sources as iron. Steel is a jack-of-all-trades metal - good availability, decent raw stats, fairly receptive to magic and not too heavy... It's this quality that makes steel so universally applicable. It's not the best at any particular job, but it's never bad at it, and you could create an army equipped with steel almost as easily as one equipped with brass.
Mithril: Lighter than steel and highly receptive to magic, mithril is a great material, but hindered by its rarity, an army of pure mithril would be an incredible feat, and the advantage for your standard footsoldier of mithril compared to steel would be minimal, making it an expensive way of essentially showing off. Just because your sword is harder than steel doesn't mean the sharp parts are going to make you any more or less dead, and not everyone has the talents that make it worthwhile.
Adamantium: The hardest, rarest metal. Slow to gather, harder than any other metal, and legendarily.... heavy. Adamantium armour would give bonuses to defence as well as making the defence that's there more likely to be applied against the thing hitting it. Things covered in heavy adamantium won't be fast however, but it's still the only metal strong enough to cut other metal like tissue paper.
This is just the metal, and ignores all sorts of more esoteric materials, but shows how each has its place, its value, and hopefully goes hand in hand with the tenets of fantasy - Rare metal is rare, people using it are rare, armies using it exclusively? Extraordinary.
For unique materials, this goes slightly differently - there are potentially two types of non-standard resource, one I've not mentioned yet.
1: Gathered special resources - the unique honey from a tree, hunted ivory, venomous bloom, pseudo-dragon pets. All these are gathered from the environment already special in some way or another.
2: Created special resources - Enchant an item yourself? Or your hero found it falling off the back of a haunted lorry? That's a created special resource, possibly one of a kind. But this isn't the only means of producing a created resource. Consume food to create poisons or drugs (representing the sacrifice of arable land for sleep-flower production), work basic leather into improved leather, have your mages guild create some scrolls of fireball and much more.
How much effort this may be, and how far this is taken (have a smithy automate to create swords, or assume a sword comes from the raw material directly?) for the player is optional; each building in a city might be globally or individually activatable, quietly consuming resources to produce things whilst the main city production works on important projects (since it makes zero sense that a city can only do one thing at a time, military unit or building, ideally this production would include units as well, quietly consuming population and the necessary equipment for it, but I accept this idea may be unwelcome). A single menu giving global control (and a toggle to make individual cities ignore this global control) would make it easy to manipulate even the biggest empire, whilst a city-specific menu would allow fine-tuning and more controlled production for expensive, vulnerable or specialist units.
A magical nation might be able to gather enough mana to allow every unit built to have a magical weapon. A dwarvern kingdom might have squads equipped with dwarf-crafted extra-thick mountain plate armour. An elven nation might have superior composite bows and automatic machine crossbows... The goal with created unique equipment is customisation and versatility without clutter and tedious (and mandatory) micro management.
These then fall into three different potential effects:
- Unique equipment material with its own bonuses - dragonscale or rune-smithed steel as gathered and created equivalents.
- Unique material with it's own permanent advantage - Unlike equipment material, this would revolve around skills and permanent bonii - a poisoned weapon gives a permanant "poison" skill to the unit, magic honey gives 10% maximum HP, a bow (gives a permanent bonus of being able to fire arrows)...
- Unique one-time use abilities requiring resupply - Unlike permanent advantages, these abilities would be usable once (or however many times available based on the item), then greyed out and unusable until the unit enters the area surrounding a city or trading post (outpost is possibly a better term, and any outpost could potentially be upgraded to a village etc) where it will automatically resupply from available resources. Rather than magic +10 Max HP honey, why not magic "restore 50% HP to a target within 1 square" honey that can be used once? One off abilities provide variety and tactical versatility, yet still be handled on the equipment side of the unit design.
C) Training time ignores equipment.
What exactly is the difference between a knight and a footman? Or a knight and a squire?
It's not equipment. A footman with a mythril plate outfit is still a footman, he still fights as well, he still runs in fear from the Scary Ghost monster, he is still a footman.
The best part about Master of Magic was all the various units. The Dark Elven Nightblade is not just a better equipped Dark Elven swordsman. The thing that makes the difference is the abilities, and it should be these abilities that determine how long it takes to train a unit - churn out well equipped peasants if you like, it won't be cheap, but it will be quick. The time involved in creating the materiel is included in how rapidly you acquire the resource in the first place, and how quickly it can be turned into equipment. This is separate from the production of a unit, and is required up-front (you can't train a unit on sticks, then switch them to steel and expect no change). More on this in section 2.
2: Worthwhile unit design.
The quality of a unit is a combination of its training, its race (selected from the available population in your empire no less), it's equipment, and its special equipment. Attack, Defence, Health and Speed are fine, but there's so much more to a unit. I have to disagree with the suggestion that it's "what you equip them with" that's interesting, there's zero point in making individual armour materials changeable, only their appearance, and that for nothing outside of aesthetics.
There isn't the option to equip them with fighter-bays, a point-defence laser array, a few M.I.R.Vs and a subspace forcefield. A sword is a sword, an axe is an axe. Both swing, both are pointy, and the only difference is 1 point in stats that you never think of again after it's done. What's interesting is what the unit can do with their gear, unless that gear gives them a specific strategic impact by itself.
So.... What differentiates a unit?
A: Stats and gear.
Obviously. The stats are the most fundamental part. Inferior weaponry penalises the attack stat, lighter weaponry sacrifices some points of attack for more attacks per round, superior weapons might improve both. I don't believe that just four stats covers it (how well does it defend against magical attacks? Or fire? Ice? There's a fine line between covering everything necessary and not overwhelming the player (and I admit it zigzags a lot), but surely this is too shallow for an engaging design element? Worldmap speed? Combat speed (not necessarily the same)?
Equipment choice is just as important as equipment material, as is whether a unit has a primary and secondary weapon.
Primary weapon: Two handed weapons are good for penetrating armour, but one-handed weapons allow shields. Shields are incredibly good at defending yourself with (far more than is usually accounted for indeed), but a one handed weapon lacks penetration power against armour. Even the difference between a thrusting rapier and a slashing scimitar are important to consider when facing things that have inhuman resistances.
This falls roughly into "bludgeoning", "slicing" and "piercing" damage, and this doesn't cover "cannonball", "flaming", "chilly", "poison" or any of the more unusual units; even "biting" is a viable damage type here... And of course "magical".
And I haven't even mentioned ranged weaponry yet (which introduces the reload time for ranged fire), or armour (movement speed is every bit as fundamentally important to tactical gameplay as any stat mentioned, skirmishing raiders and flanking bonuses make for an interesting battle), mage weapons, or even two-weapon fighting.
Secondary weapons: "Weight" is an important aspect of equipment. Ranged units with just bows will fare poorly in melee combat using just their bows as staves, but spend a few more resources and sacrifice a little combat speed and you can kit them out with shortswords, or even give your knights some crossbows (or a wand of starbolts) giving them a secondary fire option they can use when the situation demands it (chosen automatically on situation). In this way, a squad of knights could take out the faerie archers with their iron swords, then whip out their steel maces to turn a group of skeletons to powder,
Armour: Equally important to weapon choice is armour. Ignoring the varieties for the most part, there's light (padded cloth, leather, salamander-scale, fur....), there's medium (chainmail is cheap, light, and if mithril probably counts as light armour), and there's heavy (platemail with greaves and gauntlets), each with varying degrees of impact on mobility and weight (this becomes important if you include terrain effects, heavy armoured knights fare sometimes lethally badly in the mud).
Finally, unit changers - equipment that vastly changes the unit. This was mentioned up in 1b - a ranged primary weapon makes for a primarily ranged unit. A mount makes for a mounted unit type for drastically improved health and mobility (infantry might go places a standard mount can't, however). A unit with a mage-weapon might default to being a mage-type unit, and can take mage abilities, each type with their own base stats.
Even whether a unit is male or female might have an impact (physical abilities ignored, a female would be the appropriate choice to handle a nymph and her charming smile for example).
B: Traits and abilities.
What makes a knight a knight, and not a footman? Just the name? What's in a name, will a peasant by any other name still whiff as badly, or fail to hit the broad side of a barn so sweet?
Skills and abilities are the lynchpin of variety - the things that make a unit mechanically different. I mentioned above a ranged unit with a bow, or a mage unit getting a wand, but a swordsman is fundamentally identical to any other swordsman regardless of weaponry... but let's give those two identical swordsmen some abilities:
Swordsguy A:
Sturdy (+10% HP and defence).
Counterstrike (Automatically attacks enemy units moving out of adjacent squares).
Indomitable (+5% attack and defence for each adjacent enemy unit after the first).
Swordsguy B:
Grace (+20% combat speed, +5% defence against area attacks that aren't directly targetting it).
Flanker (If this unit attacks a target which is adjacent to another friendly unit, it gets a 25% damage bonus).
Skirmisher (This unit can move and attack in the same round without penalty).
And there we are, two units that work together but feel entirely different. A is a defensive unit, built to keep units next to it and to survive the experience. B is a skirmisher designed to move in, attack, then move away again.
These traits would be the primary difference between different races, fantastic units and unit types.
A few more examples:
Universal:
Stealth (requires light armour): If a unit moves into certain terrain squares (trees, marshland, long grasses), with no enemies nearby, the unit becomes undetectable until it moves (unless moving through compatible terrain), shoots, or a unit moves adjacent to it. Once revealed, a unit cannot rehide until two rounds have passed.
Magical talent: The unit gains a weak magical ranged attack (limitted ammo / encounter), or if it's a ranged unit, improves its missiles to become magical with a bonus to hit and damage.
Fire Elemental (requires magical talent and "level 2"): The unit's weaponry attacks deal an additional 10% fire damage where appropriate.
Burrow (Fantastic monster ability): Unit burrows into the ground and can move at 1/2 speed in total concealment. It must emerge to attack.
Specialist (weapon): +10% ranged damage and accuracy with the appropriate weapon type.
Dwarf (Racial): +10% health, -20% combat movement.
Dark Elf (Racial): All units start out with magical talent.
Gnoll (Racial): +20% attack for melee units, +5% combat movement.
Ranged Primary Weapon: Ranged unit:
Focus-firing: Attacking a unit already attacked by other friendly ranged units this round gets a +10% hit chance.
Sniper: If firing unseen from stealth, the unit deals an additional 30% damage.
Explosive arrow (requires Fire Weapon and "level 3"): This unit's arrows explode on impact, damaging surrounding units.
DeadEye: Accuracy penalties due to range reduced by half.
Quickdraw (Requires bow): Reloading speed reduced, allowing more attacks per round.
Extra ammo: Doubles ammunition/encounter.
Mage weapon (requires unarmoured): Mage-type unit.
Spellpower: Ranged magical damage is increased by 10%.
Overpower: Total magical shots available per encounter is halved, damage is increased by 50%.
Healer: Gains a one use healing spell per encounter.
Armoured mage I: Can be equipped with light armour.
Warrior training (blunt): The unit can use primary blunt melee weapons instead of wands.
This is naturally just a few, default level abilities, but serves to indicate the massive array of things that can be achieved with them, even with a standard unit.
Skills versus Equipment:
You can refit equipment on any unit in a town, but skills and traits are permanent (and accumulate a few more, as the unit approaches their at highest level), defining parts of a unit. Unlike equipment, which has a fixed number of slots, each unit can accumulate, say, up to three traits on creation (and optionally, given an automatic level-plan to follow straight from the gate), and end up with three more skills (and with various prerequisites of other traits to go). A unit created with no traits would train more quickly whilst three abilities would take many turns (dependent on city quality and the particular skills), but the 0 trait unit could only pick three traits (and without prerequisites, they would be limitted to weaker skills in general) meaning there would be a permanent power difference between a highly trained specialist and a cheap auxilliary.
Equipment would stay as Weapon Slot, Armour Slot, Shield Slot, Secondary Weapon, and two or three special items and never increase.
Fantastic units may have many more, but also won't often get more, or have any variety if they do, whilst heroes would have the most potential traits available, determined by their basic properties as heroes.
This trait system and combined material system, or something along similar lines, would provide meaningful design decisions - choices that drastically alter the behaviour and capabilities of a unit rather than bland numerical tweaks.
Well, there we are. Sorry for rambling on, I do love the subject matter. Hope it was at least interesting for everyone who read it.
