I have a bee in my bonnet to run a kind of high school isekai game, and this set of rules just kind of came together. The HD/saving throw rules, if you're interested, are based on this thread speculating about the combat system used in the original Blackmoor game.
Working Title: I Can't Believe My Whole School Got Transported to a Fantasy Dimension Just Before Summer Break
Just assume that anything not covered here you don't have to worry about until I say you do.
Character Creation
The stats represent what kind of high school kid you are. For each, roll 3d. Half that roll, rounded down, is your Defense for things related to that stat. You have one-third the roll, rounded down, advances to divide between its skills:
- ARTS, craftiness and matters of taste. Skills: cooking, mending, nuts-and-bolts, taste.
- GOTH, self-reliance and dedication to the bit. Skills: animals, literature, mending, stealth.
- JOCK, morale and physical condition. Skills: animals, cooking, scouting, sports.
- NERD, analysis and specialized knowledge. Skills: book smarts, literature, nuts-and-bolts, scouting.
Skills with no advance have no rating. One advance for a 5th-Rate, two for a 4th-Rate, three for a 3rd-Rate, four for a 2nd-Rate and five for a 1st-Rate skill.
Then, give your character
- A name and class year.
- One or more named people you care about at school. These can be other players' characters but don't have to be.
- What they have on their person and in their bag. This can be whatever you want, within the bounds of teen stuff.
Harm and Saves
In circumstances of peril, roll harm dice (HD) appropriate to the danger. A normal adult trying to do you harm is 1HD, while you'd roll 2HD for every 3 normal teens.
When rolling HD, discard all 6s and add up the other dice to determine the harm. Teens are taken out if they take 3 points of harm, and adults if they take 4.
When the character is able to do something to defend themselves, make a saving roll of 2d; if the roll is less than the appropriate Defense, reduce the harm taken by up to the amount rolled. Protective gear improve a Defense by 1 or 2, but the gear is damaged if that difference saves you. A risky plan and space to try it can also add 1 to Defense.
Skill Checks
When presented with a challenge, a skilled character may make a skill check. Their chance of failure is their Rate in the skill plus 1-3 if they lack each of information, time or tools. If this chance is 1-5, they pass if a roll of 1d is greater than it.
An unskilled character doesn't usually get to make a check. A lack of the appropriate information, time or tools can each increase the chance of failure.
If the chance of failure is 6 or higher, the roll fails unless a roll of 2d is 12 or higher. A character with a stat of 6+ adds 1 to this roll, and one with a stat of 8+ adds 2.
- Animals. Check to calm or handle an animal.
- Book Smarts. Check to diagnose a problem or follow a procedure.
- Cooking. Check to preserve or stretch supplies.
- Literature. Check to find or know relevant information.
- Mending. Check to repair clothing or gear.
- Nuts and Bolts. Check to make or repair simple structures and machines..
- Scouting. Check to find food, paths, shelter or water.
- Sports. Check to perform athletic feats.
- Stealth. Check to avoid notice or hide something.
- Taste. Check to color reactions to your art, music or presence with a feeling.
