Usually, a game starts with a very rough concept.

For example, let's consider the RPG we'll be making in this book. I might have the idea that this game would be a linear turn-based RPG adventure. It's a very rough concept, but that's OK—while it may not be a terribly original concept, it's enough to begin fleshing out and creating a design document from.

The design document for the game is based on the previous rough concept. Its purpose is to elaborate on the rough concept and describe how it works. For example, while the rough concept was linear turn-based RPG adventure, the design document's job is to take that further and describe how the player moves around the world, how the turn-based combat works, combat stats, game over conditions, how the player advances the plot, and a lot more.

You should be able to give your design document to any person and the document should give them a good idea of what your game will be like and how it works. This, in fact, is one of the big strengths of a design document—it's incredibly useful, for example, as a way of ensuring that everyone on a team is on the same page so to speak.

This one goes without saying. Every RPG—and I do mean every RPG—has these basic concepts.

Statistics, or stats, are the numbers that govern all combat in the game. While the actual stats can vary, it's common to have stats such as max health, max MP, strength, defense, and more.

As players progress through the game, these stats also improve. Their character becomes better in a variety of ways, reaching maximum potential at (or near) the end of the game. The exact way in which this is handled can vary, but most games implement experience points or XP that are earned in combat; when enough XP has been gained, a character's level increases, and with it, their stats increase as well.

It's common to have classes in an RPG. A class can mean a lot, but generally it governs what a character's capabilities are and how that character will progress.

For instance, a Soldier class might define that, as an example, a character is able to wield swords, and mainly focuses on increased attack power and defense power as they level up.

Very few role-playing games can get away with not having magic spells or special abilities of some sort.

Generally, characters will have some kind of magic meter that is consumed every time they use one of their special abilities. Additionally, these abilities cannot be cast if the character does not have enough magic (the term for this varies—it might also be called mana, stamina, or power—really, anything to fit the game scenario).

The game is set in an open field. Players will encounter enemies who will drop loot experience, which will increase the player's stats.

While not in combat, players explore the world in an isometric view, similar to games such as Diablo. In this view, players can interact with NPCs and props in the world, and also pause the game to manage their party members, inventory, and equipment.

When interacting with NPCs and props, dialogue may be triggered. Dialogue in the game is primarily text-based. Dialogue boxes may be either linear, the player simply presses a button to advance to the next dialogue page, or multiple-choice. In the case of multiple-choice, the player is presented with a list of options. Each option will then proceed to a different page of dialogue. For instance, an NPC might ask the player a question and allow the player to respond "Yes" or "No", with different responses to each.

A shop UI can also be triggered from a dialogue. For example, a shopkeeper might ask the player whether they want to buy items. If the player chooses "Yes", a shop UI is displayed.

While in a shop, players can buy items from the NPC.

Gold can be attained by defeating monsters in battle. This gold is known as a type of enemy drop.

While the game is paused, players can do the following:

The player has a list of party members. These are all the characters currently on the player's team. For instance, the player may meet a character in a tower who joins their party to aid in combat. Note that in this book, we will only be creating a single party member, but this will lay the foundations of creating additional party members in your future developments.

Each character in the player's party has the following equipment slots:

Player characters have different classes. A character's class defines the following elements:

The game will feature one player character and class. However, based on this player character, we can easily implement more characters and classes, such as a healer or black mage, into the game.

While exploring the game world, random encounters may be triggered. Additionally, combat encounters can also be triggered from cut scenes and story events.

When an encounter is triggered, the view transitions away from the game world (the field) to an area specifically for combat (the battle area), an arena of sorts.

Combatants are divided into two teams: the enemy team and the player team (consisting of the player's party members).

Each team is lined up, facing each other from the opposite ends of the battle area.

Combatants take turns, with the player team going first, followed by the enemy team. A single round of combat is divided into two phases: decision and action.

Firstly, all combatants choose their action. They can either attack an enemy target or cast an ability.

After all combatants have decided, each combatant executes their action in turn. Most actions have a specific target. If, by the time the combatant executes their action, this target is not available, the combatant will pick the next available target if possible, or else the action will simply fail and the combatant will do nothing.

This cycle continues until either all enemies or players are dead. If all enemies are dead, the player's party members are awarded with XP, and loot may also be gained from the defeated enemies (usually, a random amount of gold).

However, if all players have died, then it is game over.

Every combatant has the following stats:

Actions during combat are divided into three categories: attack and ability.

Once all enemy combatants have died, the player wins the fight. Upon winning the fight, the player is rewarded with random loot, and experience points are divided between party members.

As party members earn experience, they will level up.

The amount of experience required to go from one level to the next is given by the following formula:

f(x) = (xa) + c

Here, x is the current level, a is a positive value greater than one (affecting how steeply the curve increases), and c is the base offset, which is the amount of experience required to go from level 1 to level 2. This defines a simple exponential value increase. The a and c values are defined by the character's class.

To get the total amount of experience required to level up from the current level, the preceding formula is calculated and summed for each level up to the current level. For instance, if we want to know how much total EXP is required to get to level 31 (from level 30), we calculate it in the following way:

f(1) + f(2) + f(3) + … + f(30)

When a player levels up, their stats increase and they may also learn a new ability. Stat increases and learned abilities are defined on the character class.

The maximum level of any character in the game is 50.

If all players have died, either during combat or in the field, then the game ends.