A short history of assigned difficulty in Guitar Hero, Rock Band, Clone Hero, & YARG, as well as an intro to a new metric, a formula, & a Python tool for calculating difficulty from song data.
The github: https://github.com/Staycation44/fretwork/
Test data CSV to look up specific songs: https://github.com/Staycation44/fretwork/blob/main/metrics/FullTest_metrics_08052026-1308.csv
0:00 Intro
0:52 Difficulty History (Guitar Hero & Rock Band)
2:53 Modern Difficulty (Clone Hero & YARG)
5:30 Metrics – NPS / Notes Per Second
6:05 Metrics – VPS / Variability Per Second
7:50 Calculating Difficulty
9:36 Using fretwork
10:19 Official song data exploration
12:14 Conclusion
Background songs/charts:
Megalodon – Jarvis9999
Convergent Rays – Unlucky Morpheus / CSC QUAG #2 / Charted by John Titor
Killer Queen – Queen (Wavegroup Cover) / Guitar Hero / Harmonix
Open – Olly Steele / CSC Crystallizer / iZenPenguin
Black Widow of La Porte – John 5 / Guitar Hero: Warriors of Rock / Neversoft
King Aura – Seda / CSC Code Red Vol 1 / ΩHM
Will to Survive – Lutharo / CSC March 2022 (Female Led Acts #2) / ThundahK
Players featured:
@JustJoshinCH Supernovae FC
@acai28 Penger 0 ghost FC on YARG Default
@randyladyman Blindfolded TTFAF FC
@CarnyJared Cosmic Embassy grind (FC coming soon)
& me playing much worse in the backgrounds
Special thanks to @aWiseMoose for his dedicated archiving of FCs and chart comparisons
Sources for my project/this video:
TheNathannator’s chart docs: https://thenathannator.github.io/GuitarGame_ChartFormats/
scan-chart repo (helped me understand some concepts): https://github.com/Geomitron/scan-chart/
Mido (Python midi library): https://mido.readthedocs.io/
TheBagelMan’s Daniel (inspired the render view): https://thebagelofman.github.io/Daniel/
CSC’s difficulty guide: https://customsongscentral.com/diff-guitar/
Fullcombo.net’s difficulty guide: https://www.fullcombo.net/clone-hero/clone-hero-difficulty-rating-index/
Fullcombo.net’s difficulty proposal: https://www.fullcombo.net/revolutionizing-clone-hero-an-exponential-scale-approach-to-song-difficulty-grading/
Rock Band hidden values: https://rock-band-customs.gitlab.io/authoring-dtas.html
Vice History of Guitar Hero: https://www.vice.com/en/article/the-oral-history-of-guitar-hero/
Where I found Iain Simon’s book: https://www.gamedeveloper.com/design/book-excerpt-inside-game-design-harmonix-music-systems
Archive of Harmonix Q&A quote: https://web.archive.org/web/20250708042251/https://www.giantbomb.com/rock-band-2/3030-20714/forums/harmonix-and-tiers-10187/
RB3 Customs Book: https://rhythmgamingworld.com/rock-band-3-customs-book/
osu! SR explainer: https://osuppcalculator.com/blog/osu-star-rating-explained/
Etterna MSD explainer: https://community.etternaonline.com/t/what-is-msd/2265
Etterna Calculation architecture: https://deepwiki.com/etternagame/etterna/2.3-difficulty-calculation-system
source
