Call of Cthulhu - the system.

What you need to know…

The game is focused on investigation and horror: Call of Cthulhu RPG is a game where players take on the role of investigators who explore mysteries and uncover the supernatural horrors lurking in the world. Players should be prepared to engage in investigative work, such as searching for clues and piecing together information to solve mysteries.

Sanity is a crucial aspect of the game: Sanity is a vital statistic in the game, and players should be prepared to experience terrifying situations that can result in the loss of Sanity points. This can lead to the character becoming increasingly unstable or even losing their mind entirely. Players should be prepared to roleplay the psychological effects of such experiences.

Combat is not the focus: Unlike other RPGs, Call of Cthulhu RPG emphasizes investigation and horror, and combat is not the central aspect of the game. Players should avoid engaging in combat unless it is necessary, as it can be deadly and result in the loss of character lives.

The game is based on the works of H.P. Lovecraft: The game is heavily influenced by the works of H.P. Lovecraft, an American writer known for his horror stories. Players should familiarize themselves with Lovecraft's writings to better understand the game's themes and setting.

Character creation is important: The game heavily relies on character skills and abilities to solve mysteries and overcome challenges. Players should invest time in creating well-rounded characters with a range of skills to maximize their effectiveness in the game. They should also work with the game master to create a character that fits the game's setting and tone.

For those new to Gamer's Plane there's a handy guide for how to set up characters, write posts, use the dice roller etc.

https://gamersplane.com/forums/thread/2656/

Rolls during play.

Often the Keeper (GM) will call for skill rolls. Everything is a 1d100 / % roll, with the intent to get under the skill to succeed. Sometimes a Hard Success (50% of skill level) or Extreme Success (1/5 of skill) is needed or will give a better result. If you think a particular skill might be useful, go ahead and roll and if the keeper deems it appropriate, it will be taken into account.

Rolls can be impacted by Bonus or Penalty Dice. If this is the case, roll and extra d10 which will count at the 10's of the % roll. For a Bonus die, take the better result, for a penalty take the worst.
ie' rolling 1d100, Charles gets a 57 vs his skill of 50 and rolling a bonus 1d10 gets a 2. That makes the best roll 27, a success!

Pushing Rolls
If you fail a roll, you can choose to try to push the roll, doing something extra but more risky. descibe what you are doing and roll again. If you fail a second time, something bad will happen.

Luck
You can also spend from your Luck pool to push a roll into a success (or even make a success into a Hard success). Be careful! Sometimes you have to roll against your Luck and if you use up your pool, Lady Luck will not smile on you! Note you can't Luck a Pushed roll or Luck your way out of a Fumble.

I don't expect too much in terms of crafting your posts, but note a Couple of things that will help us that are fairly standard on Gamersplane

Post as your character when writing In character postsWhen you character is speaking, use BOLD TEXT

Thoughts can be represented with Italics

If the Keeper addresses you in a note, use the note tag to respond. I don't anticipate this scenario will involve much in the way of private notes but I do make use of them

Writing in Character.

There is a drop down menu when you post that will allow you to select your chaacter to speak as: