How do you compute the cost of new units?

[erelsgl]

I am studying game development, and particularly interested in mathematical methods for balancing units.

In particular, I would like to ask the faction developers in this forum: when you invent new units, how exactly do you determine their cost? Is it just intuition, or is there some formula or rule-of-thumb that you use?

I understand that the cost may be modified after playtesting, but how do you determine the initial cost (before playtesting)?

Thanks

[Ravana]

Comparing it to existing units.

[erelsgl]

OK, and what if you have a unit with stats that are not identical to any existing unit?

[Ravana]

Look closest weaker and stronger units cost. It only gets complicated with unique abilities and specials, then it is just guessing.

[lhybrideur]

Same for me. I look at similar units or if it doesn't exist look at 1 stronger and 1 weaker and do some kind of mean of both.

[IPS]

Well , there are various things you have to consider about balancing.

First of all, not all units have to be cost efficient, some units are intended to be intentionally cost ineficient because it's part of the faction's gameplay (Mages in loyalists are highly cost ineficient, but that is countered by the real high cost efficiency of loyalist spearmen); this is a case in which loyalist are forced to be mostly a pierce attack type faction and Mage an unit that is a powerful fire attack unit but that is not cost efficient. Why is this like that? Default era has something particular that not that many people noticed ... in that era there are no units that are resistant to both fire and pierce (apart of dwarves) ... drakes being weak to pierce but very resistant to fire, woses very resistant to pierce but very weak to fire, skeletons being the same case as of woses, silver mage is the same case as of drakes, BOTH pierce and fire elements in that era complements almost perfectly being the only exception dwarves that are just slightly resistant to fire (10%) and resistant to pierce (20%) , double if steadfast dwarf.

So I did somewhat overextend about that topic, but found necessary to explain why some units are cost efficient and why others not. But I will give you things that always you have to consider whenever designing units and defining costs.

1) Not all attack types have the same rarity

Spoiler:

Usually in almost any era, there are various attack types that are more common (pierce and blade at most), which usually if a cost effiicient fighter bases their high damage in that attack type is not as impactful as if it had the same damage but at a more exotic attack type as of Fire or Cold or even Impact.
- Blade and Pierce: Most common attack types, units being commonly neutraly resistant to these attack types.
- Impact: At most cases, the most valuable physical attack type, it usually counters some units that are resistant to blade and pierce (skeletons for example).
- Cold: A not very common attack type (at least in default) that is not as valuable as fire in default era. Can be used to take certain advantage over certain cases (cold to counter drakes, cold to deal +10% damage againist default's heavy infantry which are 40% pierce resistant, 50% blade resistant and 10% impact resistant but -10% cold resistant and some other cases.
- Fire: In default era, actually the best attack type as only drakes and silver mages are highly resistant to this attack type. Commonly useful againist almost everything in default.
- Arcane: This is really debatible, but depends too much on the era. In default the use they gift to arcane is making it the least common of attack types in that era but too many units being slightly weak/resistant to it (20% arcane resistance for all humans, 10% for dwarves, 0% for all orcs, -10% for trolls and elves) if you look at these cases arcane is looks not giving any advantage againist most cases. Also, let's mention where arcane gives a brutal advantage .... arcane is a powerful counter of undead which most known cases are of ghost (-10% arcane resistant but HEY, this unit has HALF health, which is basically taking a little more than double of damage than physical attacks!) , skeletons being -50% arcane resistance, walking corpses -40% arcane resistance and drakes -30% arcane resistances. Arcane as seen in default era, is a powerful counter for specific units and which its use is completely optional.

Ofc, you can make your own era and give a different role to these attack types or even implement new attack types, but have in mind about giving a specifc role to each attack type because if you end abusing of that, you would basically become your era into a game of rock/paper/siccors which lacks of clinch and woulf end at feeling something that was just implemented "because yes and you have to get used to it!" fact that to gameplay is somewhat ugly.

2) Too many stats to consider:

Spoiler:

There must be a certain balance in the stats of the unit that you're designing, in case it's balanced then you can price it. First of all, an unit has to be inevitably useful because it's too cheap but it's sincerelly useless (dies too quickly, almost null pressence in the field, etc) then that would make doubtful if it's worth buying the unit because remember the fact that when an unit is slain it gives XP to enemies. Second is that if the unit is let's say very cost ineficient and the faction does need it, players would be forced to buy it less commonly because of feeling worse spending some golds in such unit. Let's mention at here some stats.

- Health: This is a important stat, usually cost efficient fighters have a good proportion of health for its price (spearman costing 14g and having 36 HP, orcish grung costing 12g and having 38 hp, elvish fighter having 33 HP and costing 14g , etc).
- Damage: This is also another important topic, this is what defines how grunts having a much higher ration of HP per gold spent than spearmen or elvish fighters costs a whole 2g less. Grunts are 9-2 just that, while spearmen are 7-3 pierce mele +first strike which if both at favorable time of day the difference is even more notisable (11-2 vs 9-3 if not strong). While Elvish fighters are constant 5-4 but have no times of -25%. Look that grunts damage is never high enough even if in favorable time of day and that aren't the best units to last hit something if too weak, so spamming grunts gives you a terrible versatily because of itself being a less complete unit than spearmen or even elvish fighters that can even 3-3 pierce ranged.
- Movivility in overall: the more an unit can move, the more possible amount of possible moves you can do with it in a specific turn ... more ways to positionate it even from afar. Movility is easy to explain in two variables which are the amount of movement points (which means how many movement action points has) and movement costs which defines how many movement action points you need to move over a specefic terrain type. Usually more movible units have lower damage because they're used to grab villages faster and give extra gold for you or even steal enemy villages more easily. Or if in the case that a very movible unit has the same damage and health as a regular fighter it ends costing more.
Important note: Many autors of era, doesn't consider well this aspect at units balancing units. Even giving +1 movement point to a very cost efficient unit can end in a devastating advantage or if not considering at all in pricing better movement costs which means in higher liberty on movement over rough terrains. Best example of why drakes are that expensive is MOVILITY advantage because of having better movement cost than almost any default like units.

- Resistances: some units are resistant to certain attack types, this has to be considered in its price. Isn't that hard to understand this, but will let to be known some things that have to be considered in this. Resistances tiers is the complete opposite of attack types; I refer, being resistant to more common attack types is better than being resistant to a more rare attack type, so in overall lines +10% blade resistance is much better than +10% fire resistance. At least in lv1 stats 10-30% resistance to a common physical attack is worth a little less than a whole extra +1 damage in an attack of 3 strikes, reason is quite simple, +1 damage helps you at dealing more damage againist everything while being resistant to a single attack type allows you to counter in a defensively way units with a single type of attacks. Bonus resistances can be gift as a perquisite to justificate some extra stats after being slightly cost ineficient.

- XP and leveling: Ye, this is a very important point when defining costs to unit, how fast they can advance. In default there are various not so cost efficient units that as part of their lower cost efficiency is justificated by leveling up slightly faster than units with the same cost... best examples are poacher at costing the same than elvish fighter (But at being useful in Knalgan because being the toughnest unit in forests in that faction) but poacher at being so much less cost efficient is justificated by leveling super fast and when advancing to lv2 it levels up into an unit that hasn't as much pressence (offensively) than various other lv2's (elvish marskman.... or even elvish hero or dwarvish steelclad).
Additional Note: too many era authors end at making their eras too disbalanced by now knowing the correct values of XP for certain units.

3) The Use of Specials and Auras

Spoiler:

This is another topic, attack special or auras are extras that can be used to make an unit be better or worse. Ofc, the more impactful and powerful a special or aura is the more it has to increase unit's price to make it feel fair. +Magical in default like is a precision booster that increases a lot the damage output of various units making them cost more, because if you price an archer as 14g and give them +magical and let them be 14g you're defenetively making something wrong by allowing an unit that doesn't even need a such powerful special to cost that amount... ofc, stronger specials, the higher handicaps an unit needs to have to be fair (leadership units are weaker as compensation of the extra aura compared to their non leadership variant, elvish captain vs elvish hero). And even considering that certain specials need skill or positioning to allow you to exploit them well (specially +Charge and +Backstab respectively...) isn't criteria of not considering these when pricing units... because if any of both is well used, the difference is a WHOLE x2 damage by costless !!! even in the case of charge being costless is a GRAVE problem because the side that uses the unit with +charge can decide to WHAT ENEMY UNIT to attack, allowing the player to use that unit in whatever he considers it favours at most (and this is specially devastating and impactful at more skilled players)

And well, rest depends in your own balance criteria, creative and intution, but it's best to study various example at some eras and comparing them to units that you're really sure why they cost what they cost. Best non-default era to study to learn balancing actually are **Extended Era** and **Rashy Era** which are two of the eras that are monst inspired in default balance.

Edit: balance notion is adquired by becoming a more skilled and attentive player and knowing how to use well various factions and their challenges. It's important that for certain time you use as many factions and recognize which units or strategies may be over-rewarded or too ineficient.