# Catalog expansion and advertised variety

Offline study of the September 5, 2026 public Steam catalog. Uses paid released
games outside content descriptors 3/4, with current tags and descriptions,
recorded dates and the previously verified KOF XV date correction. Main years
2019–2025; January–August 2025 and 2026 compared separately. 81,619 rows enter
the union of these periods. Neither this metadata filter nor app IDs constitute
manual quality screening or title/edition deduplication.

The question is about breadth and concentration in current storefront
positioning attached to release cohorts. Historical tags, real mechanical
diversity, originality, influence, actual copying, and gameplay quality are not
recovered from these data. Newer named tags can make old activities appear new.

## Measurements

- All top-20 tags; a fixed transparent set of 181 activity/genre tags; and each
  game's highest-ranked tag in that set. Each game contributes one total vote
  spread across its retained tags. The primary-label representation gives it
  exactly one vote, including an unclassified label when necessary.
- Shannon effective diversity is exp(entropy): the number of equally common
  labels giving the same entropy, not a count of true genres. Simpson diversity
  and top-ten shares are saved as additional concentration views.
- Activity pairs use at most the first five ranked activity tags. Counts of
  observed pairs are supplemented by exact hypergeometric expected richness in
  a uniformly drawn 3,000-game sample, including games producing no pairs.
  A second measure counts expected pairs occurring at least five times.
- Coverage sensitivities: exactly twenty returned tags; exactly the first three
  activity labels among games with at least three; at least 100 reviews; and a
  fixed broad ten-tag view. Those use common 1,000-game rarefaction, kept separate
  from the headline 3,000-game comparison.
- Neighbor comparisons sample 3,000 games within each of 2019, 2021, 2023 and
  2025. Tag overlap is Jaccard similarity; the eligible set requires at least
  five non-administrative tags. Lexical overlap uses TF-IDF words and bigrams in
  short pitches, screened for at least fifteen Latin words, English-oriented
  function-word presence and predominantly ASCII text. This text subset does
  not represent every language in Steam. A common current vocabulary/IDF is
  fitted across 2019–2025, not as a historical prediction exercise.
- Nearest neighbors exclude self, then same normalized developer-credit string,
  then both same credit and publisher. Names do not prove different teams.
  Alternate editions can still appear. Two 2,000-game random replicates and a
  3,000-game one-per-credit sample are retained. All comparisons within a
  configuration use equal sample sizes across years.

The selected highest-overlap examples and random neighbor examples are saved.
They include edition variants and formulaic puzzle descriptions. Neither
similar text nor similar tags establishes that two games play identically.
No inference of AI authorship or game lineage is made.

## Reproduction

Use `../.venv/bin/python` from this directory:
`study.py`, `neighbors.py`, `sensitivity.py`, `charts.py`, `validate.py`.
All scripts are offline. Sources remain unchanged. The root network collection
policy remains paused. `findings.md` contains the interpretation, also delivered
in chat; CSV tables and frozen neighbor memberships support inspection.