A little while ago I posted about retrofitting the AD&D 1e Surprise Mechanic as a combat system (blog link) and then a RPG system (blog link).
I’ve now gotten this rules light RPG system down to a one page PDF: 
here
But, here it is also in a less portable web page version:
^^ Despite the name, I don’t appear to have the wherewithal to remove the boarder around the above image ^^
Player Characters (PCs) statistics (stats)
S – SKILL; fighting skill / physical prowess
M – MAGIC; ability to do magic
A – ARMOUR; used to reduce damage done to RESILIENCE
R – RESILIENCE; equates to life / health (0 is unconscious, -1 is dead)
T – TRICKERY / THIEVERY; non-magical specialist type skills
Starting and advancement
PCs start with 1 point in SKILL and RESILIENCE, and have 1 further point to put in any one of their stats.
When a PC ADVANCES, the PC gains +1 point to add to any stat. Only ARMOUR is limited to a maximum of 3.
Stat interactions
There are no classes per se, but advancement in one area comes at a cost to other areas, so multi-classing is difficult:
In the set ‘SKILL, MAGIC and TRICKERY’: for every 3 points gained in one stat, then -1 point from the other two.
For every 1 ARMOUR, then -3 MAGIC and -2 TRICKERY.
Opponents and EXPERIENCE (XP)
To ADVANCE a PC must gain new XP equal to the cube of the PC’s highest stat. So, if the PC’s highest stat is 4 then 4×4×4=64 XP is needed. Defeating an opponent gives XP equal to the square of the opponent’s highest stat.
Each increment in an opponent’s stat should be thought of as an exponential increase. So, an opponent with 6 SKILL is as good as it gets at fighting, e.g. a dragon. A Lich would have 6 MAGIC. Some illustrative opponents:
| Orc S M A R T: 1 0 1 1 0 (1 XP)
Ogre S M A R T: 3 0 2 2 0 (9 XP)
Dragon S M A R T: 6 3 3 9 1 (81 XP) |
Zombie S M A R T: 1 0 0 1 0 (1 XP)
Werewolf S M A R T: 4 0 1 3 0 (16 XP)
Vampire S M A R T: 5 4 2 4 2 (25 XP) |
Combat
The player rolls a d6, and if the roll is equal or lower than their PC’s SKILL, they hit (a roll above SKILL is a fail).
An unarmoured opponent’s RESILIENCE is reduced by that die roll.
An armoured opponent reduces the die roll by their ARMOUR; but this number is never lower than 1.*
Example 1: a PC with 4 SKILL rolls 3 on a d6, which is a hit. An unarmoured opponent would have their RESILIENCE lowered by 3. If the opponent had 2 ARMOUR, their RESILIENCE would only be lowered by 1.
Example 2: a PC with 4 SKILL rolls 5 on a d6, which means they fail to hit.
Damage to RESILIENCE can be spent over multiple opponents. However, to carry damage over to the next opponent, the current opponent’s ARMOUR and RESILIENCE must be zero. So, in Example 1, a roll of 3 would defeat two orcs: 2 points to reduce the first orc’s ARMOUR and RESILIENCE to 0, and 1 point to defeat the second orc.*
Magic
A PC can cast a number of successful magics per day equal to their MAGIC. Failed magics do not count to the tally.
The player describes the magical effect the PC is trying to achieve. Optionally, using no more syllables than the PC’s MAGIC, e.g.: fire < fireball < cone of fire < delayed fireball < localised fireball < localised cone of fire etc.
The magic is successful if the d6 roll is equal or lower than the PC’s MAGIC (a roll above the PC’s MAGIC is a fail).
The potency of the magic equates to that roll; a 1 being low potency and a 6 being the most potent possible outcome.
Example 3: a PC with 4 MAGIC rolls 3 on a d6, which means the magic works and on a scale of 1 to 6 it is rather successful. The 1 to 6 scale should be thought of as an exponential type scale, so a 3 is much better than a 1.
For example, if the magic was: Magic Missiles, it might generate 3 magic missiles each harming 3 RESILIENCE; Stinking Cloud, this might cover 30 feet and last for 3 rounds. In a one-page RPG system with a free-form magic system, the GM will need to arbitrate, preferably discussing the possible scaled outcomes with the player first.
Example 4: a PC with 4 MAGIC rolls 5 on a d6, which means the spell fails.
Magical items and bonuses
Any modifiers, like ‘plus weapons’ (e.g. +1 sword) will distort the d6 game mechanic markedly, because in this system a +1 is a big modifier. So, it is probably best to imbue magic items with useful/narrative properties rather than pluses.
… That’s it!
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Me on DriveThru; at the moment I’m mainly pimping my procedural:
:: High Seas ‘Hex Crawl’ – In the Heart of the Sea,
:: Wilderness Hex Crawl – In the Heart of the Unknown,
:: Dungeon/network generator – In the Heart of the Delve & Dangerous
Goblin's Henchman 