Figure 4. Three decades of mechanic evolution. Games published per year carrying each mechanic, 1990–2021 (59,415 game-mechanic pairs from 21,721 ranked games, BGG snapshot 2022-01-18). Stacked bands: the 12 most common mechanics in the window plus the highlighted story mechanics (14 named bands); all 137 remaining mechanics are aggregated into the explicit gray “Other mechanics” band, so the stack height is the true total. A game with k mechanics is counted once per mechanic — bands measure mechanic usage, not game counts. Accent colors mark the story: Cooperative Game (vermillion) grows from 10 games in 2007, the year before Pandemic, to 119 in 2021; Legacy Game (purple) and Campaign / Battle Card Driven (orange) emerge after Risk Legacy (2011) and swell through the Gloomhaven era. Toggle Log scale (lines) to compare growth rates: the y-axis switches to log₁₀ and bands unstack into lines, since stacked areas are not meaningful on a log axis. The visible rise of every band also reflects BGG-era survivorship — older games are listed less completely than post-2000 releases — and the 2020–2021 dip is listing lag in the 2022-01 snapshot (recent releases had not yet accumulated the 30-rating minimum), not a real publishing decline.
Source: Kaggle BoardGameGeek dataset (bgg-kaggle-matrix-2022-01-18), boardgamegeek.com. Window and band rules: ontology/SPEC.md §4.4.