Besides being the oldest horror rpg Call of Cthulhu from Chaosium is also a classic and one, that I have returned to many times playing either campaigns or oneshots, usually set in the 1920s or played in the present using the Delta Green setting. Recently I have returned to Call of Cthulhu and I have played some of the older published adventures focusing on adventures, that can be played in a single session.
In recent years my gaming have been influenced by various impro-techniques, failing forward, saying yes and using the Gumshoe concept as found in Trail of Cthulhu (I still hope to get to run a Night’s Black Agents game) to create a smooth flowing game, where the simple Basic system rules support the mood, I want to create. The Call of Cthulhu rules are simple, at times almost too simple, but it allows for a casual use of the rules, so they can step into the background, while I focus on the setting and the mood. I do look forward to trying a more complex version of the basic rules, as I have invested in the RuneQuest: Rolepaying in Glorantha rulebook and look forward to trying the game.
Playing the older Chaosium modules have, however, revealed, that many of them are not that good. The oldest are mostly variations on haunted houses or dungeon crawls with ghouls, deep ones and other minor cthulhuid beings in place of orcs and goblins, and other adventures are not presented very well needing a close reading.
I will be playing more Call of Cthulhu in the future, and I hope to play more Delta Green as well, as well as trying other spinns on the Cthulhu theme.