First off, the stats are different. You have..
Dexterity (Involves ranged weapons, dex skills, reflex saves)
Wisdom (Determines wis skills, sanity points (wis score x10), will saves)
Constitution (Determines wound point threshold, toughness checks)
Strength (Involves melee/throwing weapons, str skills, fortitude saves)
Charisma (Cha skills, wealth checks, psychic power)
Intillegence (Int skills, number of proffession trained skills gained, occult)
How Skill checks work:
This system is much more linear since alot of newbies don't like remembering alot of rules nor in a horror campaign is it good because it cheapens the creepy/pasta.. Skillchecks work pretty simple. Every skill has a stat, and you look at that stat, roll a d20, and try to roll below that stat amount to succeed at a check.
Alternatively, it can be a trained skill. A trained skill is automaticaly put to 20. Meaning you only have a 5% chance (Rolling the 20) to fail at it. Determing number of trained skills is equal to intelligence score divided by 4 rounded down but no less then one. So if I have a score of 11. I gain two trained skills.
For example, Jim Profit is a security guard. He has an 8 intelligence. So he gets two trained skills and the proffession security guard allows him a plethora of choices. So he chooses listen and firearms.
Saving Throws:
Saving throws are the same as with stat checks for skills. And can also be trained skills. Saving throws however are more likely to come with a dice roll penalty, or make you have to roll several times for succeess. Here's an example...
Jim Profit's buddy Patrick is walking down the halls of his college and sees this dog that looks like a giant brain with four legs like a dog and a tail. He looks again and it isn't there anymore. Patrick is forced to make two will saving throws, and if he fails even one he takes 2 san damage as a sign he's been shaken up.
Combat:
Combat is where things get really cool. I want this system to be realistic in how death comes unexpectedly.. Let's say Jim Profit had been in Patrick's shoes and saw "the brain dog". How would he have reacted? Well he wouldn't have waited for it to dissapear. His security guard training would've kicked in and he had gotten out his gun and shot at it. So he has to take three steps.
Step One: Uses either his dexterity score or if he has it, his trained skill. Which he does. He succeeds, onto step two.
Step Two: The typical cheapo handgun his security company gives him has a Damage DC of 13. This means that he has to roll below a 13 to "damage" the brain dog. So now he has to roll this second d20. Depending on if he succeeds or fails he goes onto step three anyway.
Step Three: If Jim Profit succeeds, the brain dog has to make a constitution or toughness if it's trained skill check, and if the brain dog fails. It dies.
However, if Jim Profit failed his damage DC, the brain dog simply takes a number of woundpoints as described on the weapon. (Let's say in this case 2) A creature, any creature, can accumulate a number of wound points equal to their constitution score before they die. And woundpoints can be healed by medical supplies. Wounds from damage can also result in sanity loss from bodily shock. But it's rare, and should only be done sparingly..
Jim Profit has managed to kill the brain dog. And goes up and gets a closer look. Seeing this freaky abomonation actually deals more san points then if he had just left it alone like Patrick did! He has to make a will save or take 10 san damage! Way to go Jim Profit! Why not just shoot Jesus while you're at it?! Jim Profit doesn't have to worry too much about the san loss though. San loss can be recovered like woundpoints a number of ways. Therapy, reading a nice book, a goodnight's rest. Or in his case getting PG-13 with his girlfriend Julz!
If he reaches sanity points 0 though he dies or atleast becomes an npc character.Psyhic Powers:
Psychics exist and can use personal enlightenment and self awareness to do supernatural ****! This is why I decided to make it charisma based. There could be different psychic powers avaliable, and based on the character and how they roleplay, the DM decides what powers to give them and how "good" he is with them. Cause even though he could have psychic as a trained skill, does not mean all psychis are created equaly. So instead of relying on his 20 score. Make him roll several checks to see if he ever flops on a 20. Psychics shouldn't be perfect.
Occult:
Like psychics, but without the personal power and instead use incanations, binding circles, tomes, crystals, whatever! Occult can be alot more diverse both in effect and how it's performed. It can also incoporate more penalties as if you utter the incantation wrong or misdraw the binding circle.. who knows what could happen!
So how do you like my "Call of The Cthulhu d20 Lite"?