DevDiary 6 - Combat, Part one
Combat, Part One
Hello there! I am Boian Spasov and it is my pleasure to welcome you to a DevDiary on a subject that I’ve been wanting to write about for a long time – combat! Yeah, it’s a big one - there is so much to talk about that a single article won’t be enough and you can expect a second combat DevDiary down the road.
As stated in our first DevDiary “Game Vision” the combat is one of the pillars of Jagged Alliance 3. It is a deep, involved and realistic experience and is the single aspect of the game that we iterated on the most during development.
Combat in Jagged Alliance 3 is turn-based with your entire team taking a turn, followed by the enemy team. During your turn you are free to activate your characters in any order and intermix action between them.
A typical character turn in many tactical games can be described as simply as “I move to this position and attack with this skill”. This level of abstraction is perfectly fine for these titles and we have seen how it can create deep and engaging gameplay, but for a simulative game like Jagged Alliance 3 we wanted more precise level of control over your character’s actions. How exactly do you move - will you hustle recklessly or carefully crawl to the target location? How exactly do you attack? Do you take your time to aim carefully? Will you attempt to cripple the target shooting a burst at their limbs or gamble for a killer headshot instead? This is achieved with several game mechanics working in concert, the most important of which are the Action Point system, the movement stances, the weapon firing modes and the body parts targeting system.
All actions that a character takes during their team’s turn are limited by their available number of Action Points (AP). A simple action like crouching may cost only a single Action Point, while a more time-consuming action like a carefully aimed attack with a rocket launcher may consume most of the characters’ AP for the turn. Attack actions may be modified by spending additional AP to aim more carefully, increasing the chance to hit precisely with the net benefit from Aiming also depending on the weapon and the character stats.
An average rookie merc has around 10-12 AP per turn. This number is increased for veteran mercs and when conditions are favorable, like at high morale, but never too much. We intentionally kept the numbers relatively low to ease the mental calculations related to Action Points that players do each turn. However, even though the available number of AP is always displayed as an integer, it is internally stored with higher precision and certain very simple actions like moving at a short distance effectively cost only a fraction of an action point.
Characters are always in one of the three movement stances – standing, crouching or prone. Movement actions have different costs based on the chosen movement stance – crawling takes significantly more time than running the same distance but will realistically hide you from sight when you are behind an obstacle and is generally safer against firearm attacks and explosives. Conversely, if the enemy will attack you with a melee attack you will be at a disadvantage if you are crouching or prone.
When moving you can always lock your chosen movement stance, manage stances manually or let the game manage them automatically, switching to standing when this will optimize AP usage while moving but still ending the movement in your desired stance. This approach is not without risks – your characters are more exposed if they are running around standing between safer spots and if you expect to provoke an enemy attack it might be better to move crouched or prone.
Firing Modes and Body Parts
You have three important decisions to make when attacking – how many additional AP you are willing to spend aiming, what firing mode do you wish to use and a what body part to target. Firing modes are pretty straightforward - an automatic weapon, like an AK-47, is able to attack not only with single shots but also with burst an auto-fire attacks, shooting more bullets at the expense of accuracy and AP cost. Since bullets are simulated individually this also tends to create more chaos on the battlefield, but I will talk more about the bullet simulation further down.
With a double-barreled shotgun you can offload both barrels with the same attack, but you will have to reload afterwards. A dual-wielding character may alternate between firing with both weapons or just one of them by selecting the appropriate firing mode.
Body part targeting allows you to try to hit a specific body part and inflict additional effects with the attack. Headshots are often difficult to pull of but deal massive damage, while arm and leg shots are often useful for crippling enemies that you will not be able to finish off during the current turn. Melee attacks may be targeted at the enemy neck, inflicting various crippling effects that depend on your weapon of choice.
(Note that some of the following screenshots demonstrate some debug functionality available only to developers. These shots are marked with “Dev mode enabled” in the bottom left corner and are not representative for the game visuals as seen by the players.)
Firing at a particular body part is only possible when you have a clear line of fire to it – as determined by the geometry of the level. Some body parts may be armored, presenting interesting moment-to-moment tactical choices during the battle.
Body part targeting is never possible when you don’t have clear sight to the enemy like for example when you are firing at an enemy behind a wall…
Hitting someone behind a wall – what kind of sorcery is this? I apologize for getting a bit ahead of myself here, but I will explain immediately. Hitting enemies through walls and even through other enemies is possible in Jagged Alliance 3, thanks to our bullet simulation logic.
The bullet simulation logic involves a set of calculations for each individual bullet fired, based on the caliber and type of the bullet as well as the materials encountered along its path (armor, bodies or environmental objects). Both accurate and inaccurate attacks may have various unexpected effects because of it, like penetrating an enemy body to hit another enemy, grazing an ally by accident or destroying some of the environment on the bullet path.
The bullet simulation and the destruction system took considerable amount on effort to implement and support but all the effort was worth it because at its core combat in Jagged Alliance 3 aims to be a realistic experience, one that would not be possible without a realistic simulation running behind it. Which neatly brings me to the final, and perhaps the most important, point that I want to discuss in this DevDiary…
No Visible Chance-to-Hit
Each time you are setting up an attack in Jagged Alliance 3 you will see various factors that affect it both increasing and decreasing the chance for the attack to be accurate. What you will not see is an exact, precise chance-to-hit percentage number.
During the early years of development Jagged Alliance 3 displayed visible chance-to-hit, just like XCom and many other tactical games do. What we observed time and time again during our playtest sessions was that people were focusing on this number to the point where they centered their entire gameplay style around it, like never attacking when it is below a certain threshold. It also created moments of frustration and disappointment as in-your-face randomness sometimes tends to do.
We don’t feel there is anything wrong in principle with visible chance to hit. There are many immensely successful tactical games out there that play exactly like this and CTH was present even in some of the most popular JA mods. It is, however, not the kind of a core experience we had in mind for Jagged Alliance 3, a game meant to represent firefights in their entire chaotic and messy glory. We wanted an experience that allows you develop a sense for certain situations, a game that makes you focus on your surroundings and the unique combat situation instead of a number in the interface. That was our reasoning when we decided to experimentally hide the chance-to-hit number in the interface and observe if the players will approach the combat situations differently afterwards. The first confirmation that we were on the right track came from none other than Ian Curry, the creator of Jagged Alliance, and many more followed in the months after – players were more involved now, found the situations more unpredictable and the game more unique and distinctive. Encounter after encounter, they were gradually developing a sense of mastery and generally had way more fun this way!
We are fully aware that the decision to remove chance-to-hit will never sit right with some players but still feel that it is the crucial design decision that made our combat “click” and feel right. There are many tactical games with perfect and detailed CTH information out there, but too few where you play “by feel” as was the case with the classic Jagged Alliance!
Thank you for reading the first combat DevDiary. Here are some of the subjects we might explore in the next one – Weather Effects, Night and Darkness, Stealth and Overwatch/Interrupt Attacks. If you are interested in any other aspect of the combat gameplay, please suggest in in the thread below.
By THQN Roger