Gameplay - Modular Ability System

The game’s core gameplay system—a modular ability framework—is built in Unreal Engine on top of Epic’s Gameplay Ability System (GAS). It allows players to customize their skills using modules collected during a run.

Core idea
Players can reconfigure their skills at runtime (inspired by Noita). To support this, the game uses a large pool of modular base/modifier plus a runtime “executor” that converts the player’s setup into an ordered cast sequence.

Base: Defines what the skill does and how it targets.

Examples:

Select the nearest enemy

Fire a projectile and select the first enemy hit.

Modifier: Defines what happens on hit/target.

Examples:

Damage the target

Heal the target

Flow of control

Read player input (drag and drop) in UI ->

Update inventory and weapon component ->

Read player input (click for casting) ->

Retrieve data in component to skill executor ->

Compile the spells and apply any modifiers ->
Cast the spell and wait for next input

Scripting - Player-programmable skills

Player-programmable skills are executed base on gameplay ability system, a Unreal Engine official plugin that support games with many ability. This system uses tag to grant effects to characters that has GAS component.

The flow of data

Scripting - Random Stream and Seed

Replayability is critical for roguelite games. A shared seed lets players reproduce the same run, compare outcomes, and discuss builds under identical conditions, benefiting the growth of community.

Paraclysm uses a single-seed, multi-stream RNG approach inspired by Slay the Spire. Separating randomness into dedicated streams keeps runs reproducible and makes outcomes more consistent, which supports players that wants to go for a Save/Load play style.

All procedural systems use a shared Random Stream seeded by RunSeed. Streams are created during initialization, stored in the Game Instance, and provided to systems as needed.

Streams

Paraclysm currently uses five RNG streams:

Loot stream

Room stream

Shop stream

Event stream

Mob spawn stream