Gameplay Systems Overview

This document provides a high-level overview of the main gameplay systems included in RPG Engine v6. Each system has its own detailed technical documentation; here we focus on scope and purpose.

Combat Systems

Firearms

RPG Engine v6 includes a full firearms framework suitable for shooter and survival gameplay. It covers weapon handling, aiming, recoil, reloading, multiple ammo types, and weapon-specific data assets.

Firearms integrate with the state system, inventory, and animation layers, allowing actions such as shooting, reloading, aiming down sights (ADS), and weapon switching to be controlled through shared character states.

Melee Combat

The melee system provides close-combat gameplay with multiple attack types and hit zones. It supports different attack directions, combo logic, blocking, and cinematic cameras for powerful strikes.

Melee attacks are integrated into the same state and animation framework as firearms, allowing a single character to use both ranged and close combat systems.

Grenades

The grenade system supports multiple grenade types (for example, explosive, smoke, stun, gas or EMP-like behaviors). It covers throwing logic, type switching during gameplay, and interaction with other systems such as armor and survivability.

Grenades are handled as their own combat module and use inventory and item data structures for configuration.

Armor and Damage

Armor is integrated into the damage pipeline and can protect against specific types of damage. Different armor pieces can offer varied protection and may interact differently with special ammunition or environmental effects.

The damage system processes incoming hits through multiple layers, including skills, buffs, armor, and raw health. Hit reactions can vary depending on damage direction and hit location, including different death animations based on the angle of the attack.

Aiming, ADS, and Weapon Modifications

The combat framework includes aiming and ADS (Aim Down Sights) behavior, together with the ability to modify weapons. Scopes, silencers, magazines, grips, flashlights, and other modifications are supported and can affect aiming, recoil, sound, and other weapon stats.

Weapon modifications are integrated into both the visual and gameplay systems and are driven by dedicated data assets and configuration structures.

Character, Progression, and Survival

Stats and Survival

RPG Engine v6 includes a survival-oriented stats system. Core stats typically include health, hunger, thirst, energy, temperature, breath, and hygiene or body contamination.

These stats are not cosmetic; they affect gameplay, such as movement efficiency, perception, survivability, and detection by certain abilities.

Buffs and Debuffs

A dedicated buff system manages positive and negative effects on the character. Buffs can provide passive bonuses (for example, increased health or damage) or conditional protection layers, while debuffs can apply states such as burning, freezing, or knockout.

Buffs and debuffs are integrated with the damage pipeline, stats, and combat systems, allowing them to influence both incoming and outgoing damage as well as movement and perception.

Abilities and Unusual Skills

Abilities and so-called Unusual Skills form an extended ability layer. These can include telekinesis, teleportation, scanners, vision modes, dash moves, area healing, summoning AI helpers, smell-based detection, and other special actions.

These abilities are integrated with the same mediator and state architecture as other gameplay systems, meaning they can be activated, validated, and managed through shared state rules.

Progression and XP

The project includes progression mechanics such as levels, XP, and skills. A skill tree or similar structure can unlock passive and active abilities, improve resistances, and tune survivability or combat performance.

This progression layer connects to combat, survival, and abilities, so that long-term growth has a direct impact on gameplay.

Respawn and Revive

A respawn system handles what happens when the character dies in singleplayer and multiplayer. A revive or recovery layer may also exist for cooperative scenarios, allowing players or systems to bring a downed character back into action.

Respawn logic is handled through dedicated components and is integrated with save/load, stats, and equipment.

World, Interaction, and Systems

Inventory and Equipment

RPG Engine v6 uses a grid-based inventory system inspired by extraction shooters. Items occupy cells, backpacks expand inventory space, and equipment slots handle weapons, armor, clothing, and other worn items.

Inventory and equipment are data-driven, using data tables and data assets to register items, define categories, and describe rules for how items are equipped, stacked, or used.

Loot and Interactables

The project includes a generic interaction system for world objects such, pickups, doors, stations, and other interactable actors.

Interactables are configured to work with the inventory and state systems, and can represent weapons, melee items, bags, usable items, quest objects, and more.

Vehicles

RPG Engine v6 includes a vehicle system with support for entering and exiting vehicles, driving, passenger modes, damage, fuel, lights, and visual deformation (for example, via morph targets).

Vehicle gameplay is organized as a separate module and uses its own state and data configuration while still fitting into the same overall character and mediator architecture.

Building System

The building system allows players to place, upgrade, and destroy structures. Buildings have health and can be tied to resource consumption, requiring materials such as wood, metal, or glass from the inventory.

Building actions integrate with crafting, survival, and combat where relevant, and are implemented as a dedicated gameplay module.

Crafting

A crafting system enables players to create new items, weapons, or resources from existing materials. Recipes can use special conditions, and crafting is integrated with inventory and progression.

Crafting rules are data-driven and can be extended by adding new recipes and conditions.

Doors and World Puzzles

The project includes different door types and world-interaction puzzles. Examples include regular doors, code-locked doors, locks that require turning mechanisms, wire-connection puzzles, and doors that require keys.

These interactions are built on top of the shared interaction and state systems.

CCTV System

A CCTV system provides security cameras and control panels. Players can use camera feeds to observe areas, which can interact with stealth, AI behavior, or mission design.

Cameras and panels are implemented as world actors that tie into UI and interaction systems.

Map and Minimap

The world map and minimap systems provide navigational tools. They support markers and integration with quests and points of interest.

The map UI is connected to the quest and world systems so that objectives, locations, and other information can be presented consistently.

Quests, Dialogues, and Trading

A quest system supports quest data, objectives, and tracking on the player side, as well as quest-giving NPCs. Dialogues provide one-sided and two-way conversations, including optional facial animation for characters.

A trading system enables NPC vendors, allowing players to buy and sell items. This connects inventory, economy, and progression into one loop.

Save and Load

RPG Engine v6 includes a unified save/load system used in both singleplayer and multiplayer. Saves store character stats, inventory, equipment, appearance, quests, and world state where appropriate.

The system uses different naming schemes for singleplayer, host, and client saves but shares the same general structure across modes.

Character Customization and Wardrobe

The project supports character customization, including full MetaHuman and Mutable integration. Body parameters, head parameters, and appearance data are stored in save files, making customization persistent.

An in-world wardrobe station provides a place where players can change appearance and loadout during gameplay, not only in menus.

Settings: Graphics, Gameplay, Audio

The project includes configurable settings for graphics, gameplay, and audio. These settings are exposed through UI and can be adjusted by the player.

Changes in settings affect rendering quality, control behavior, and sound, and are integrated with the broader UI and persistence layers.

Movement, Traversal, and Technical Layers

Movement and Locomotion

The movement system covers basic locomotion such as running, crouching, jumping, and related animation logic.

Locomotion integrates with weapons, equipment, and the state system, ensuring that movement and combat behaviors are consistent and data-driven.

Traversal and GASP Integration

Advanced traversal includes features such as climbing, ladders, scalable obstacles, and parkour-like movement. GASP or similar traversal tooling is integrated into the state architecture rather than used as an isolated plugin.

Traversal states are managed through the same mediator and state system, allowing clean interaction with combat, animation, and input.

Swimming and Breath

Swimming and breath management are part of the movement and survival layers. Breath is treated as a stat, and time spent underwater interacts with that stat and can lead to consequences if it is exhausted.

Input Layer

The input layer is built on Enhanced Input. Input actions are mapped to gameplay states rather than directly to component logic.

Multiple input mapping contexts are used for UI, on-foot gameplay, and vehicles, and can be switched at runtime based on the current context.

UI and Common UI

The project uses Unreal’s Common UI framework for menus, HUD, inventory, and other interface layers. CommonActivatableWidget and related types provide stack-based navigation and gamepad-friendly control.

UI is integrated with the save/load, settings, inventory, and session systems.

Multiplayer Session Layer

The multiplayer session layer handles hosting, joining, and managing sessions. It covers creating sessions, searching for sessions, connecting, and handling session-specific save/load behavior.

The architecture is listen-server oriented, with shared core systems across singleplayer and multiplayer.

AI

The AI system uses Behavior Trees, EQS, and customizable parameters to define behavior for different AI types (melee, ranged, guards, and more).

AI integrates with perception, combat, movement, and Unusual Skills, and can be tuned via data assets and presets for different difficulty levels or behavior patterns.