Historical clue formulations

• Gloom — 2026-06-07
• It's difficult to see through — 2013-12-25
• Visibility reducer — 2013-02-10
• Gloom — 2012-05-19
• Gloom — 2003-02-20
• Darkness — 2001-11-25
• Darkness — 2001-06-15
• Darkness — 1996-11-28