t1k:designer:economy:shop-offering

Field	Value
Module	`economy`
Version	`1.7.2`
Effort	`high`
Tools	—

Keywords: economy, offerings, shop, store

How to invoke

/t1k:designer:economy:shop-offering

Game Shop Offering

When This Skill Triggers

Designing pick-N-of-M item offering mechanics
Implementing weighted rarity item draws
Adding pity timers for guaranteed rare drops
Making shops show synergistic or diverse offerings
Designing shop economy (gold budget, pricing scaling)
Implementing reroll or refresh mechanics
Tuning strategic choice difficulty in offers

Offering Algorithms

Weighted Rarity Draw (Standard)

Rarity    | Base Weight | Adjusted Weight (depth 5+)
Common    | 500         | 400
Uncommon  | 300         | 300
Rare      | 150         | 200
Epic      | 40          | 80
Legendary | 10          | 20

Normalize weights to sum = 1000, draw with Random.Range(0, 1000)
Increase higher-rarity weights by depth to reward run persistence

Pick-1-of-N Rule

3 choices = optimal: enough diversity, not overwhelming
Mobile: 2 choices acceptable to reduce decision fatigue
Never offer 2 items of same rarity in same slot (guarantee variety)

→ See references/offering-algorithms.md for weighted draw code, diversity enforcement, exclusion lists

Pity Timer System

Pity Counter Pattern

per-run counters:
  shops_since_rare      = 0   (reset on rare+ offer)
  shops_since_legendary = 0   (reset on legendary offer)

on each offer generation:
  if shops_since_rare >= 4:     force at least 1 rare slot
  if shops_since_legendary >= 12: force 1 legendary slot

Display pity progress (“Rare guaranteed in N shops”) — reduces anxiety
Pity resets per-run only; do NOT persist across runs (breaks tension arc)

→ See references/offering-algorithms.md for full pity implementation patterns

Synergy-Aware Offering

Scoring Each Candidate Item Against Current Inventory

synergy_score = (adjacency_matches * 2) + (set_completion_bonus * 3) + (type_bonus * 1)

Sort candidates by synergy_score; pick top 60% slots from high-score pool
Reserve 1 of N slots for “wildcard” (0% synergy weight) — enables discovery
Cap synergy weight at 60% to prevent “obvious best choice” every offer

Diversity Enforcement

Track item type histogram for current run
Penalize item types player already has 3+: weight * 0.5
Bonus weight for item types player has 0 of: weight * 1.5

→ See references/offering-algorithms.md for synergy scoring, diversity formulas

Shop Economy

Gold Budget Per Floor

gold_earned_per_floor = base_gold * (1 + depth * 0.1) + enemy_count * gold_per_kill
shop_price_common     = gold_per_floor * 0.15
shop_price_uncommon   = gold_per_floor * 0.25
shop_price_rare       = gold_per_floor * 0.45
shop_price_legendary  = gold_per_floor * 0.80

Player should afford 1 common item most floors, 1 rare every 3 floors
Price scaling ensures same relative cost throughout run

Reroll Mechanics

Type	Cost	Limit	When to Use
Single item	10% item price	Unlimited	When 1 offer is weak
Full refresh	30% avg offer value	1x/shop	No offers fit current strategy
Premium reroll	Hard currency	1x/run	High-stakes decision point

→ See references/shop-economy.md for pricing tables, reroll cost scaling, gold distribution

Strategic Choice Design

Choice Difficulty Spectrum

Too Easy:   1 great item + 2 useless items → player feels robbed of real choice
Too Hard:   3 roughly equal items → cognitive overload
Sweet Spot: 1 clearly good + 1 situationally good + 1 build-enabling wildcard

Aim for “hard choice” 30% of the time (memorable decisions)
“Easy choice” 50% (progression momentum)
“Trap choice” 20% (tests player knowledge; must be learnable)

→ See references/strategic-choice-patterns.md for difficulty tuning, trap item design

Anti-Patterns

#	Anti-Pattern	Problem	Fix
1	Always synergistic items	No discovery; known meta only	Reserve 1 wildcard slot per offer
2	No pity timer	Dry streaks cause rage-quit	Guarantee rare after 4 shops
3	Uniform rarity per offer	No hierarchy feel	Enforce rarity diversity per slot
4	Reroll too cheap	Players reroll until perfect	Cost 20-30% of item value
5	Price does not scale	Late-game gold meaningless	Scale prices with depth
6	Only 2 choices on PC	Feels binary	Use 3 minimum on PC

Cross-References

game-economy-design — gold earn rates, sink/faucet balance for shop currency
game-roguelike-design — shop placement in run arc, gold budget per floor
game-synergy-combos — synergy scoring used in synergy-aware offering
rpg-game-design — item power tier definitions used in rarity weighting
puzzle-game-design — adjacency bonuses shown in offer UI (BackpackCrawler)

Reference Files

File	Coverage
`references/offering-algorithms.md`	Weighted draw, pity timers, synergy scoring, diversity
`references/shop-economy.md`	Pricing formulas, gold budgets, reroll cost scaling
`references/strategic-choice-patterns.md`	Choice difficulty tuning, trap items, offer composition

Gotchas

Pity timers without visibility are wasted — players need to see the bar fill or the rare-drop guarantee shifts no behavior.
Reroll cost should scale with offering value — flat reroll defeats the strategic-choice goal; players just spam reroll until they like the offering.
Synergy-aware offerings require knowing the player’s build state — if your shop doesn’t read inventory, synergy-tags are decorative.