Recipe: Currency & shop

Ingredients

• Variable coins — int, scope player, persist on, default 0.
• Config shield_price — int, default 100.
• UEFN devices: 1 Elimination Manager, 1 Button Device, 1 Item Granter (shield potion), 1 HUD Message device.

Build it

1. 1

   Variable + config

   coins (int, player, persist on) so progress sticks between sessions. shield_price in Config so designers tune economy in UEFN without redeploying.
2. 2

   Earn rule

   WHEN On Elimination → DO Give Currency coins +10, Show HUD "+10 coins".
3. 3

   Successful purchase

   WHEN On Button Pressed IF Compare variable coins ≥ shield_price → DO Decrement Variable coins by shield_price, Grant Item shield_potion, Show HUD "Purchased!"
4. 4

   Failed purchase

   WHEN On Button Pressed IF Compare variable coins < shield_price → DO Show HUD "Not enough coins". Symmetric pair: either you can afford it or you get the “nope” feedback. No silent failure.

Generated Verse

# Persistent state
te_player_stats := class<final><persistable>:
    Version:int = 0
    Coins:int = 0

# Successful purchase rule (Rule 3)
ShopButton.InteractedWithEvent.Subscribe(OnShopPress)

OnShopPress(Agent:agent):void=
    if (GetCoins[Agent] >= ShieldPrice):
        SetCoins(Agent, GetCoins[Agent] - ShieldPrice)
        ItemGranter.GrantItem(Agent)
        HUDMessage.Show(Agent, MsgPurchased)
    else if (GetCoins[Agent] < ShieldPrice):
        HUDMessage.Show(Agent, MsgNotEnough)

Variations

• Tiered shop — multiple buttons each with their own price + item granter. Each gets a pair of rules.
• Daily reset — add a last_purchase_day variable; allow once per day.
• Bulk discount — gate by a buy_count threshold for a loyalty price.

Gotchas