Grand Tactician: The Civil War (1861-1865)

[Asid]

DevBlog #3: Combat Systems Pt.1.
Fri, 23 May 2025



In this third dev diary of the upcoming Grand Tactician sequel, as well as the next ones, I'll discuss the main changes made in the game's combat systems. In short, this will bring a lot of further detail in the way battles play out, while also providing opportunities for multiple interesting historical settings in the GT-series.


Unit and Soldier Levels

Like already mentioned in a previous dev diary entry, with the new unit system, we were able to move much of combat calculation to single soldier level. This includes both ranged engagement and melee combat.

In GT1 (The Civil War) combat system, combat resolution takes place mostly on unit level. In ranged combat, the possibility of engaging an enemy unit is checked on unit level, taking into account terrain and own units (to avoid blue-on-blue, ie, friendly fire). If this check returns positive, a volley is calculated, using a complex formula (taking into account everything from terrain, formation, cover, weapons, morale, training, experience, etc.). The volley is calculated from soldier models, each aiming at a target unit in its possible firing arc. This allows the unit to fire at multiple enemy units at the same time. A number of casualties is calculated for the target unit(s), and the visual layer shows the casualties in the nearest ?coy platforms? (the unit is broken down to multiple smaller blocks, as per previous blog).

Melee in GT1 uses a very simple model - hand-to-hand combat during the Civil War was rare. In this model, the unit engaging in melee will place itself next to the target unit, slightly overlapping, to visually communicate to the player there a melee is ongoing. The actual combat resolution takes into account unit conditions and stats, and from this, casualties are inflicted on both sides. The abstraction takes into account formation, so formation A is 10% more effective in melee than formation B, which, on the other hand, may suffer further casualties from small-arms fire. Once one unit's morale falters, it will fall back or rout, while the winning unit will continue combat according to orders.

The resulting model is quite good and believable, especially if the values in the formulas are well balanced, but it still lacks detail. In ranged engagement a part of a unit will not be able to fire if the unit level check for line of sight fails, and units can only engage enemies in their front sector (except in infantry square formation, where four front sectors are calculated). Melee on the other hand is much more heavily abstracted.


Organic Combat from Soldier Level

In the rebuilt combat model, unit level is still a factor. Calculating everything on a single soldier level would be too much in terms of performance. Things like morale, cohesion, fatigue, cover, concealment, line of sight calculation (for fog of war, i.e. are units spotted or not), movement in terrain, are tracked per unit. These values are then passed on to the single soldier level for the actual combat and casualty calculation.

So, when a soldier fires his weapon, the hit probability is modified with unit-level values. Is the soldier tired? Is he well-trained in the use of his weapon? Is he familiar with the stress of combat, fighting in close order with other guns blazing right next to his ear and enemy firing back? Is he blinded by smoke? On the soldier level, does this soldier see an enemy in his dedicated sector? Does the weapon he carries reach that far (a single unit can have different weapons, so some may fire while others may not)? Can he fire at will, or is firing controlled per rank, for example? Are there friendly soldiers in the way? When pulling the trigger, all this is taken into account, plus also external effects like weather: will the weapon misfire? When the weapon fires and a hit on target is achieved, what is the impact of the projectile? Will it penetrate possible armour, and if so, will the target become a casualty? In case of artillery, how much energy does the round still have? Will it hit another soldier?

All this makes more ?organic? combat outcomes possible, as the different outcomes don?t need to be artificially adjusted.


In this pair of images, on the left we have the GT1 engagement system and on the right the rebuilt engagement system:

In GT1 the red unit is within range of the blue unit, inside the front sector fire arc. First, the line of sight check returns positive: the unit can engage. Then the actual firing is calculated from the soldier models, which allows firing at multiple units simultaneously or limiting the number of soldiers firing (due to no enemies being in the soldier?s firing arc). Casualties calculation is done on unit level, taking into account direction of fire and creating the casualties in the nearest coy platforms. This calculation is modified with flanking fire value (simulating the higher chance of hitting a soldier further back, which is not the case if engaging from the front), which increases the effectiveness of the volley. In the end, 5 casualties are inflicted, and models on the left flank of the unit change to casualty animation and then ?die?. The red unit cannot return fire, as its unit-level fire arc is pointing in the wrong direction. (What is not taken into account here is that in GT1 ,the average scale in visualization is 1:25, meaning 1 soldier model stands for 25 soldiers in the unit. To increase the visual impact, we kill more models than the calculated casualties justify. After a short time, a few more models spawn and move to ?fill the gaps?.)

In the new system, each soldier (model) is constantly checking whether it sees enemy soldiers within assigned engagement directions (a soldier can have multiple, for example, as 1st priority front, and 2nd priority to left). Depending on the unit?s firing system, the single soldiers have permission to fire or are part of unit-level controlled fire, where permission to fire is given per rank. The per-rank firing to priority direction can happen as a part of single or multiple ranks firing a simultaneous volley, and may include rotation of the ranks to move soldiers with reloaded weapons to the front. Each shot by a soldier at a soldier is calculated separately, and the outcome is decided. For example, two soldiers fire at the same enemy soldier; the first one misses, and the second one hits. The rightmost soldier picks a target further back. (Also marked is the possibility for the red unit to fire back, as in the new unit system, the left flank soldiers can turn and fire at different targets than the rest of the unit.)

Even if the result in both systems is the same, 5 casualties in the red unit, the result in the new system comes through an ?organic? calculation, as we like to say. There is no separate bonus from firing from the flank, as the increased effect comes directly from the soldier-level engagement modelling. In case the blue unit was in open order or the red unit had a bigger number of ranks or density of soldiers, the result could change drastically. In the left model, this comes from a separate single unit level modifier (casualty modifier per formation for red, firepower modifier per formation for blue), in the new model, such modifiers are not used and the result will be more realistic through organic means.

Like written previously, GT1 is very heavy on CPU usage due to a lot of calculation ongoing at all times, especially with large armies fighting. While the detail of combat has increased tremendously in the rebuilt combat system, the new engine handles the required calculations much more efficiently than in GT1, and performance is much better in similar size battles, even with 1:1 model per soldier scale vs. the old 1:25 scale.

In the next diary, we?ll take a look at the new melee system, which is very much a different beast in its own right - and there the soldier level approach has the most advantages.

Most Respy,
Gen?l. Ilja Varha
Lead Designer - Grand Engineer Corps

[Asid]

DevBlog #4: Combat Systems Pt.2.
Fri, 25 July 2025



This is the 4th DevBlog in a series where we discuss the work currently being done in developing a new game in the Grand Tactician -series. The new game and the conflict it covers has not yet been announced - but the work is progressing nicely and we're getting closer to dropping some more specific details... when we feel ready to do so.


Stages of Close Combat

In the new combat model we?ve been working on, the biggest and most visible change is in how close combat (non-ranged engagement, ie. charge and melee) works. This was a critical factor in combat and tactics before the introduction of rapid-firing weapons, even if prolonged melees became rare much earlier.

In GT1 (The Civil War) we have a rather rudimentary close combat model, focusing on melee: a unit charges another unit, when the units overlap a melee ensues. Casualties are inflicted on the fighting units, taking into account a lot of unit level factors such as unit type, training, cohesion, fatigue, used weapons, formations, number of men engaged in the melee? This continues until one unit falls back or routs.

The new close combat system is built to accommodate basically any conflict between the 17-19th Centuries, not only one specific like in case of GT1. In this new system, we have broken close combat down into multiple layers that can be described as sort of ?stages?, though they are not linear or exclude one another at any specific time - it?s just easier to break the system down this way when describing it.

A unit can end up in close combat when charging an enemy unit, being charged by an enemy unit, or when opposing units overlap one another for any reason during a battlefield movement. In the last mentioned situation the nature of the close combat is unplanned, so neither unit is intentionally engaging into melee, and no charging takes place. So, let?s focus on situations where one (or both) of the units in question deliberately engage into close combat.


The Charge and Impact

Depending on the unit and tactics employed, charging can happen in different formations and speed. A cavalry unit, for example, could charge in a linear or columnar formation, or in any specific charge formations such as wedge, and usually on the trot or gallop. An infantry charge may happen even with standard marching pace. A charging unit may try to maintain solid formation or ?break into a charge? more individually (?Hollywood style?). What is most interesting to us from this is the speed of the unit and the disposition of the soldiers within the unit (formation and its integrity).

The unit being charged may or may not be prepared to receive a charge. If we ignore fieldworks and use of terrain, the most important counter against a charge is cohesion of formation and the weapons employed. A dense hedgehog of lowered pikes or a wall of bayonets of infantry in a square formation could be sufficient to discourage a cavalry unit from charging home, and have it veer off instead, maybe discharging its firearms in anger at close distance. A controlled volley fired at a charging unit from a close range could break the formation of the charging unit and either blunt the charge or have the unit abort and disengage altogether. The unit being charged may also falter and decide to fall back in the face of the charge before properly engaged. With the use of our updated morale and cohesion systems, we can now simulate these outcomes which were much more common that prolonged melees throughout the 17-19th Centuries.


Image - Outcomes of a charge: A) the charging unit ?flinches? and does not press home. B) the charged unit ?flinches? and disengages before impact. C) Charging unit pressing home the charge and the charged unit standing its ground, resulting in an impact.

Let?s assume now, that the charging unit is dedicated and able to charge home and the target unit does not falter. What happens next is an impact, where the charging unit (could be both units) violently collides with its target in a certain formation and carrying a certain speed - let?s call the latter an ?impact speed?. First off, who shall hit whom first? The weapon used is important in the soldier-level combat model. Both the attacking and defending soldiers could be armed with weapons that can outreach their opponent. A cavalryman with a 4 meter lance would outreach a musket with a bayonet, but on the other hand could be hit first if facing a soldier with a 5 meter pike. Also important is the penetration capability of the used weapon and the armour of the soldier being hit with that weapon.

Maintaining cohesion a unit receiving a charge could blunt the charge. The impact speed carried could be drained (by loss of intergrity of the formation) and the impetus lost, as the full weight of the unit does not crash into the ranks of the other unit intact. On the other hand, if the charging unit has longer weapons (such as lance for cavalry) and can maintain its impact speed, the end result could be very bad on the receiving end, with the first line being decimated by the lances (for example) and the subsequent ones receiving the weight of the mass of horses still in full speed. Let?s call this phenomenon ?ranged melee?. If both sides are armed identically, any benefit of reach is naturally lost. If the unit receiving the charge has no proper counter against it, the formation could suffer severely in the form of casualties and loss of integrity as soldiers are pushed off their position. In the end the charging unit could either mow down, penetrate and completely shatter the target unit with the carried weight and impact speed, or the impetus is lost and either the charging unit is repelled or a melee ensues.


Image - Ranged melee logic: A) charging unit has longer weapons and the defending formation is broken upon impact. B) the defending unit is ready to receive the charge and has longer weapons, the charge is blunted. C) identical armament offers neither unit initial advantage.


The Melee

As described, a lot could already have happened before we find the men of our opposing units fighting it out eye-to-eye, dealing blows with any dedicated melee weapons, be it swords, bayonets or rifle butts. It?s very likely that at this point either (or both) unit(s) could already be about to disengage. As said, prolonged melees were not common. Even if the opposing soldiers would remain determined and the units intact, which should be rare, melee is tiring and messy business, and the party finding itself overpowered would try to disengage orderly to prevent a disaster.

In this case we have our soldiers fighting a ?close melee? (as opposed to the previously mentioned ?ranged melee?). Weapon, armour, training, morale and fatigue are important factors, but so is the cohesion and type of the formation: if the formation is shattered or spacing loose, a single soldier could be facing multiple enemies at once. Also there is the weight of the enemy formation.

In close melee, single soldiers could end up being pushed by the enemy. This will have the formation bend, while still being able to hold its ground. If the pressure gets too much, the whole unit could be pushed back, which may end up a larger battle line being bent. The depth and cohesion of formations is important, a columnar unit can concentrate its strength on a narrow front better than a linear one.

Usually, if the pressure can be maintained with determination, the line being pushed will eventually give in and break. This can be controlled, with the unit being able to reform further back, or uncontrolled, which usually results in rout.


Image - Close melee logic: A) Charging unit breaking into formation of the defending unit that stands it ground. B) Attacking unit pushing defending units, creating a bulge in the defender?s line. C) One unit is unable to withstand the pressure, formation is broken and the unit routed.


The Counter-charge and the Pursuit

When the melee ends with one side breaking (it could also end up with both sides disengaging due to exhaustion), the successful party should exploit the situation. This way the end result could be a complete defeat of a larger enemy force, a domino effect that would win the battle before it grinds to a battle of attrition ruining both armies and resulting in a pyrrhic victory in best case.

A defending unit may utilize tactics (stance) called Countercharge. When doing so, the unit will stand fast in order to repel any enemy attack and once the enemy disengages in disarray, it will immediately charge home in turn to wreak maximum havoc on the now disorganized and demoralized enemy, before disengaging in turn to regroup and to hold the line. If the attacking unit is successful, it may pursue the routing enemy unit in order to cause maximum casualties and to force the unit to surrender.

In either case, the winning unit should be in sufficient condition to exploit - an exhausted or scattered unit will not be able to pursue. A pursuing unit may become hard or impossible to control, so having fresh reserves at hand can be crucial in order to turn a tactical level success into a victory in battle. And this is of course the Art of War for the Grand Tactician - You!


Most Respy,

Gen?l. Ilja Varha

Lead Designer - Grand Engineer Corps