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The Ultimate Multiplayer Skill System (UMSS) uses a flexible, data-driven XP pipeline that supports any type of progression, including:
  • XP-based leveling
  • Use-based (“learn by doing”) systems
  • Parent/child shared XP
  • Profession systems
  • Combat XP
  • Crafting/gathering XP
  • Custom rule-driven XP sources
  • Talent progression tied to skill levels
UMSS does not dictate when or how XP is awarded — you control that entirely through Blueprints or C++. This page explains how XP works, how to award XP, how leveling is calculated, and how parent/child relationships affect progression.

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🧠 1. How XP Works in UMSS

Each Skill Instance has:
  • Current XP
  • XP Required for Next Level
  • Current Level
  • Level Cap (from the Skill Definition)
  • XP Curve (controls growth rate)
When XP is added:
  1. XP is accumulated
  2. Required XP is checked
  3. If XP meets the requirement:
    • Level increases
    • Remainder XP carries over
  4. Events fire:
    • OnSkillUpdated
    • OnSkillLeveledUp
  5. Replication syncs changes to clients
UMSS handles the leveling logic automatically.

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🎯 2. Awarding XP (Blueprint)

To give a skill XP, call:

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Award XP

SkillComponent → AwardXP(SkillTag, Amount)
You can call this from:
  • Anim BP
  • Weapon BP
  • Interaction BP
  • Crafting events
  • Gathering events
  • Quest completion
  • Ability hits
  • Timer-based tick
  • Environmental logic
📸 Screenshot Needed
Blueprint node calling AwardXP with a Gameplay Tag.

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🧩 3. Awarding XP (C++)

If your project uses C++: 
SkillComponent->AwardXP(FGameplayTag::RequestGameplayTag("Skill.Combat.Sword"), 25.f);
This is safe to call on the server only.
(Clients may request XP through RPCs if desired.)

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🔁 4. XP Curves (Level Requirements)

The XP curve defines how much XP is required per level.

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Supported progression types:

  • Flat (same XP every level)
  • Linear (steady growth)
  • Quadratic (good for profession-style skills)
  • Exponential (RPG / MMO style)
  • Curve Table (full control)
Set this inside each Skill Definition.

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Example XP Curve Rules

StyleGood ForExample Formula
FlatUse-based skills50 XP per level
LinearSurvival games100 * Level
QuadraticProfessions25 * Level²
ExponentialMMO combat skills75 * (1.5^Level)
UMSS does not enforce a specific formula.

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🌲 5. Parent / Child XP Behavior

Parent/child relationships allow ecosystem-like skills, such as: 
Crafting
 └─ Carpentry
      └─ Bowmaking
UMSS supports several XP behaviors (designer-controlled):

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A. No Shared XP

Parent and child each level independently.

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B. Child → Parent XP

When a child gains XP, the parent also gains XP.

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C. Parent → Child XP

Leveling the parent skill pushes XP into its children.

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D. Mixed or Custom Rules

You can apply custom logic in your XP-award calls to route XP however you want. UMSS does not force any specific pattern — you define the relationships.

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🎮 6. Use-Based Progression

UMSS supports “learn by doing” systems easily. Example workflow:
  • Player chops a tree
  • Tree BP calls AwardXP(SkillTag.Logging, 8)
  • Skill updates automatically
  • XP popup (custom UI) appears
  • Logging skill slowly increases
No timers, no extra systems — just call AwardXP whenever an action happens.

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🪓 7. Example: Gathering XP

Example BP logic for gathering: 
OnResourceHarvested:
    AwardXP(Skill.Gathering.Logging, 12)
You can scale XP based on:
  • Tool quality
  • Tree tier
  • Skill multipliers
  • Region buffs
  • Weight/size of item harvested
UMSS stays out of this logic — it only processes the XP you award.

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⚔️ 8. Example: Combat XP

Workflow:
  • Hit detection event on server
  • Determine weapon type
  • Award XP for the matching skill
Example: 
AwardXP(Skill.Combat.Sword, 15)
Or award XP based on damage dealt: 
AwardXP(Skill.Combat.Sword, DamageAmount * 2)

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🔧 9. Level-Up Behavior

When a skill levels up:
  1. New level is set
  2. Remainder XP carries over
  3. Level-up event fires
  4. Replicated updates are sent
  5. UI can display a notification (your custom UI)
UMSS fires these events:
  • OnSkillUpdated
  • OnSkillLeveledUp
Your UI or gameplay logic can tie into these. Examples:
  • Play VFX/SFX
  • Unlock recipes
  • Improve stat bonuses
  • Activate a talent node
  • Notify the player

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💡 10. Progress Queries (Useful for UI)

Common Blueprint accessors:
  • GetSkillLevel(SkillTag)
  • GetCurrentXP(SkillTag)
  • GetXPRequiredForNextLevel(SkillTag)
  • GetPercentToNextLevel(SkillTag)
  • GetSkillDisplayName(SkillTag)
  • GetAllSkills()
These make UI building straightforward.

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🌐 11. Multiplayer Behavior

UMSS is fully replicated.

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✔ XP is processed on the server

Clients can request XP, but all final calculations occur server-side.

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✔ Values replicate automatically

Level, XP, talents — all synced.

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✔ Level-up events fire on clients

Your UI can safely respond on each player’s machine.

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✔ Talent unlocks must be server-authoritative

The same rule applies for XP.

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🔥 12. Advanced: XP Modifiers

You may add your own modifiers outside UMSS:
  • Temporary XP boosts (double XP)
  • Region-based bonuses
  • Equipment bonuses
  • Potion buffs
  • Skill synergy bonuses
Common pattern: 
FinalXP = BaseXP * XPBoostMultiplier
AwardXP(SkillTag, FinalXP)
UMSS does not impose limits here — you build the system you want.

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📌 Next Steps

Now that you understand XP flow: 👉 Talent Trees – Build perks, branches, and prerequisites.
👉 Component Integration – Ensure your Skills Component is set up correctly.
👉 Example Implementations – See practical BP examples of combat, crafting, and gathering XP.