Cthulhu Britannica
Tags: 1930s, far future, modern, near future, Victorian Era
Cubicle 7 Entertainment: Call of Cthulhu 6 (2009 )

Investigator Weapons Volume 1: The 1920s & 1930s
Tags: 1930s
Sixtystone Press: Call of Cthulhu 6 (2012 )

Forbidden Kingdoms: Master Codex
Tags: 1900s, 1930s, 19th century, 20th century, Victorian Era
OtherWorld Creations: d20 3 (2001 Hardcover)

GM's Guide to World War II
Tags: 1930s, 1940s, Britain, Earth, Europe, Great Britain, Third Reich
RPGObjects: d20 Modern 1 (2007 PDF)

Gangbusters: The Blue Book Detective Agency Beginner Rules
Tags: 1920s, 1930s
Black Mask Games: GangBusters 4 (2016 Digest)

Gumshoe: The Hard-Boiled Detective in the Thirties
Tags: 1930s, 20th century
Sleuth Publications: Generic 1 (1985 )

Legacy of Justice: The Pulp Era
Tags: 1910s, 1920s, 1930s, M&M Superlink
Big Finger Games: Mutants & Masterminds 2 (2006 PDF)
Big Finger Games: Mutants & Masterminds 2 (2007 )

Noir Knights
Tags: 1930s, Great Depression
Cubicle 7 Entertainment: Savage Worlds 2 (2009 Hardcover)
Savage Mojo: Savage Worlds 2 (2009 Hardcover)
Savage Mojo: Savage Worlds 2 (2010 )

Noir Knights Player's Guide
Tags: 1930s, Great Depression
Savage Mojo: Savage Worlds 2 (2010 PDF)

Ravaged Earth
Tags: 1930s
Reality Blurs: Savage Worlds 2 (2008 )
Reality Blurs: Savage Worlds 2 (2008 )

The Apocalypse Machine
Tags: 1930s
Pelgrane Press: Trail of Cthulhu 1 (2011 PDF)

Cthulhu Apocalypse
Tags: 1930s
Pelgrane Press: Trail of Cthulhu 1 (2015 Hardcover)

Many Fires
Tags: 1920s, 1930s, Mexico
Pelgrane Press: Trail of Cthulhu 1 (2011 PDF)

Slaves of the Mother
Tags: 1930s
Pelgrane Press: Trail of Cthulhu 1 (2013 PDF)

Revelations of Mars
Tags: 1930s
Exile Game Studio: Ubiquity 1 (2015 Hardcover)