---
key: mechanic/progression-rewards--t241
type: mechanic
id: progression-rewards--t241
lang: en
title: 'Collections, albums and set completion'
summary: >-
Found objects fill a visible set. Gaps show what remains to discover and turn
individual rewards into a long-term goal.
updatedAt: '2026-10-21'
status: active
url: 'https://gamemechanics.pro/en/knowledge/mechanic/progression-rewards--t241/'
jsonUrl: >-
https://gamemechanics.pro/api/v1/knowledge/en/mechanic/progression-rewards--t241.json
markdownUrl: >-
https://gamemechanics.pro/content/knowledge/en/mechanic/progression-rewards--t241.md
aliases:
- Collections and set completion
tags:
- 'Progression, rewards and retention'
- Mechanics and variants
sourceIds:
- source-3817d420df0baa92
- source-1696c3167e4356ed
sources:
- id: source-3817d420df0baa92
title: 'Robert Nystrom: State'
url: >-
https://github.com/munificent/game-programming-patterns/blob/master/book/state.markdown
verifiedAt: null
- id: source-1696c3167e4356ed
title: Hollow Knight
url: 'https://store.steampowered.com/app/367520/Hollow_Knight/'
verifiedAt: null
relations:
- type: uses
direction: outgoing
label: Sources in the selection
key: resource/state-pattern
title: 'State: Game Programming Patterns'
url: 'https://gamemechanics.pro/en/resources/#resource-state-pattern'
jsonUrl: 'https://gamemechanics.pro/api/v1/knowledge/en/resource/state-pattern.json'
markdownUrl: 'https://gamemechanics.pro/content/knowledge/en/resource/state-pattern.md'
placements:
- catalogId: progression-rewards
id: t241
title: 'Progression, rewards and retention'
url: 'https://gamemechanics.pro/en/mechanics/progression-rewards/#t241'
categoryIds:
- mechanics
supersededBy: []
attributes:
preview:
updatedAt: '2026-10-21'
title: Collections and set completion
description: >-
Found objects fill a visible set. Gaps show what remains to discover and
turn individual rewards into a long-term goal.
image:
src: images/mechanics/hollow-knight-charms.webp
width: 1440
height: 810
crop:
x: 113
'y': 143
width: 1237
height: 562
game: Hollow Knight
sourceUrl: 'https://store.steampowered.com/app/367520/Hollow_Knight/'
originalUrl: >-
https://shared.akamai.steamstatic.com/store_item_assets/steam/apps/367520/ss_33a645903d6dd9beec39f272a3daf57174a6cc26.1920x1080.jpg?t=1776125684
credit: Team Cherry
rights: © Team Cherry. All rights reserved.
caption: Found charms and empty spaces
alt: >-
Hollow Knight: a collection displays acquired charms and empty positions
for missing finds.
markers:
- x: 33
'y': 55
label: An acquired charm fills its collection slot
- x: 49
'y': 55
label: An empty position represents an undiscovered object
tips:
- Make the set’s size and collection rules clear.
- Suggest a search direction without necessarily revealing the reward.
examples:
- title: Hollow Knight
url: 'https://store.steampowered.com/app/367520/Hollow_Knight/'
endsAt: null
provenance: >-
Original bilingual editorial overviews authored for gamemechanics.pro on
2026-10-20 and reviewed on 2026-10-21. Scenarios are hypothetical design
examples; prototype checks describe work to perform, not completed playtests.
Primary sources support the stated techniques and implementation context, not
every proposed variant.
license: CC-BY-4.0
codeLicense: MIT
attribution: gamemechanics.pro contributors
catalogKey: catalog/progression-rewards
---
# Collections, albums and set completion
id: progression-rewards--t241
type: mechanic
key: mechanic/progression-rewards--t241
lang: en
status: active
url: https://gamemechanics.pro/en/knowledge/mechanic/progression-rewards--t241/
Found objects fill a visible set. Gaps show what remains to discover and turn individual rewards into a long-term goal.
## At a glance
[Hollow Knight](https://store.steampowered.com/app/367520/Hollow_Knight/) · © Team Cherry. All rights reserved.
1. An acquired charm fills its collection slot
2. An empty position represents an undiscovered object
- Make the set’s size and collection rules clear.
- Suggest a search direction without necessarily revealing the reward.
- [Hollow Knight](https://store.steampowered.com/app/367520/Hollow_Knight/)
## How it works
A collection turns separate findings into a visible set whose missing entries guide further searches.
## Variants
### Mechanic variants
- Silhouettes suggest the shape of a missing entry.
- Categories connect items through a shared feature.
- Trading turns duplicates into a path toward gaps.
- Discovery history preserves location and circumstances.
## Design example
A plant album's empty mountain category suggests exploring at a different altitude.
Prototype check: Test the final collection entries: completion should have a clearer path than endless blind repetition.
## Context and limits
Progression changes player options and goals; rewards should explain new decisions and preserve useful stopping points. Each overview separates player actions, state changes and alternative rules. Examples are hypothetical design scenarios, not claims about a named game. A prototype check states an observable question for the next iteration. Existing detailed references remain separately linked from the direction map.
## Connected materials
- Sources in the selection: [State: Game Programming Patterns](https://gamemechanics.pro/en/resources/#resource-state-pattern) (key: resource/state-pattern)
## Sources and provenance
Original bilingual editorial overviews authored for gamemechanics.pro on 2026-10-20 and reviewed on 2026-10-21. Scenarios are hypothetical design examples; prototype checks describe work to perform, not completed playtests. Primary sources support the stated techniques and implementation context, not every proposed variant.
- [Robert Nystrom: State](https://github.com/munificent/game-programming-patterns/blob/master/book/state.markdown) (id: source-3817d420df0baa92)
- [Hollow Knight](https://store.steampowered.com/app/367520/Hollow_Knight/) (id: source-1696c3167e4356ed)
CC-BY-4.0 · gamemechanics.pro contributors