https://www.reddit.com/r/rpg/comments/37baz3/mage_mundane_a_quick_homebrew_fantasy_rpg_based/

On the weekend only two of my normal D&D group showed up and we decided to try out a new game. They were interested in Ars Magica but upon opening the book they realised that it wasn't going to be a quick game to come to grips with. They loved the magic system though, so we decided to shoe-horn it into the quick and easy Lasers & Feelings rpg (if you haven't played it already, give it a shot... it's a blast).

This is the quick and dirty rule-set we made up; let me know what you think and throw in your own suggestions! I would especially love to hear any other free-ish rpg systems that is simply pick-up-and-go.

MAGE & MUNDANE

A Mage is vastly over-powered compared to mere mortals, and there is barely any limits to the power they can wield (other than botching the roll and making everything worse). This usually means that Mages just apply magic to everything, including the inevitable consequences.

A Mundane is basically everyone else. Players can choose to be a Mundane characters even though they are less epic. Usually a Mundane helps their Mage by doing everything they cannot (which is usually anything not related to magic), although a Mage would argue that everything can be solved with liberal application of Magic.

CREATING CHARACTERS

1. The first step is to choose the style of your character: MAGE or MUNDANE
2. Next, choose a background or role for your character. This can be anything suitable in a high-fantasy setting. Examples: Soldier, Craftsman, Diplomat, Scholar, Doctor, or Hunter
3. Choose your number, from 2 to 5. This will determine your skills depending on the style you have chosen. (For MAGE, a low number is good for spell-casting while a high number is good for mundane tasks. For MUNDANE, a low number is good for mental tasks while high is good might tasks)
4. Select a goal from the list or create your own: Kill bad guys, Find treasure, Solve Mysteries, Prove yourself, Become Ruler, or Keep Being Awesome.
5. Choose a really cool fantasy name.
6. If you selected MAGE as your style, your character gets to specialise in 4 Forms and 2 Techniques. This forms the basis of your spell-casting ability. MUNDANE characters don't get any extra goodies, unfortunately.

SPELL-CASTING

Spells are simply the combination of a Form with a Technique. A Mage can attempt to cast any spell, even if they are not skilled in the form or technique (although this introduces a small amount of risk).

For instance, to cast a fireball would simply be Creo Ignem, giving yourself wings would be Muto Corpus, and changing the flow of a river would be Rego Aquam.

Some spells may require multiple forms or techniques to resolve properly (such as adding rain to lightning). The Mage will have to resolve each aspect of the spell individually (which means they need to roll for each particular aspect). In the above example the Mage will roll twice, once for Creo Auram (thunder and lightning) and then again for Creo Aquam (adding in the rain).

TECHNIQUES

• CREO is the act of creation from nothing, or making something a more perfect version of itself (this includes healing)
• INTELLEGO is the art of detection and revelation, and can enhance your own senses.
• MUTO is the act of transformation by adding unnatural properties to an already existing object, being or substance. It can also remove properties.
• PERDO is the act of destruction and disintegration and the opposite of creo magic. Perdo magic would just destroy the whole object or property rather than manipulate it.
• REGO is the art of control and domination. It is a way to manipulate an object without altering it's natural properties. You can put a creature to sleep, or command a tree to bear fruit out of season.

FORMS

• ANIMAL affects all beasts and creatures
• AURAM affects air, lightning and other gaseous substances
• AQUAM affects water and all other liquids except blood
• CORPUS affects the human body
• HERBAM affects plants and all other organic matter not covered in animal
• IGNEM affects light and heat
• IMAGINEM affects the senses, and is used to create illusions and images (that are not real, as it exists only in the target's senses)
• MENTEM affects the mind, emotions, memories and thoughts
• TERRAM affects the earth and minerals
• VIM affects magical power itself, as well as demons

ROLLING THE DICE

Whenever you do something risky (such as bluff the town guard, or cast a spell), you roll 1d6. You may get up to two bonus die, depending on your style.

• MAGIC SPELLS can get the bonus dice if they specialise in the form or technique of the spell. For example, a Mage specialising in Creo and Ignem would get both bonus die for casting a fireball. A mage only specialising in Corpus magic would only get one bonus dice for any Perdo Corpus spells.
• MUNDANE TASKS will get one bonus d6 if they are prepared, and another d6 if they are considered an expert at the task based on their background/role.

Success depends on beating your number, determined at character creation.

• For MAGE characters, a spell success is when you roll higher than your number. A mundane task success is when you roll lower than your number. A mundane task is anything not spell related (including mental and might).
• For MUNDANE characters, a mental task (bluffing, thinking, logic) success is when you roll higher than your number. A might task (fighting, athletics, acrobatics) success is when you roll lower than your number.
• Whenever you roll exactly your number, you get to choose whether it counts as a success or failure.

The number of successful dice you roll determines how the action resolves:

• 0 successes and the action is abject failure. Everything gets worse somehow
• 1 success and the action is partially successful, with some complications
• 2 successes and the action is completed satisfactorily.
• 3 successes and you critically succeed. You do the action and are rewarded with an additional effect

FOR THE GM

This is a quick and easy adventure builder. Roll 1d6 for each of the following

THE THREAT

1. Barbarian Horde in control of an ancient weapon
2. Cultists of a Dead God
3. Invaders from another Dimension
4. Awakened Dragon
5. Demons from the Nine Hells
6. Great Old One

WANTS TO

1. Destroy / Corrupt
2. Steal /Capture
3. Protect / Empower
4. Pacify / Occupy
5. Bond with / Dominate
6. Build / Create

THE

1. Kingdom
2. Bridge to Heaven / Hell
3. Weapon of Magical Destruction
4. Dimensional Portal
5. Ancient Ruin
6. Magical Artifact of Immense Power

WHICH WILL

1. Destroy the World
2. Reverse Time
3. Enslave all sentient beings
4. Start an invasion from another dimension
5. Rip a hole in reality
6. Fix everything

edit: We did have a house rule that a Mage could only cast a spell every other turn so that they didn't spam a spell every single turn. I left that out of the rules because I thought it should be optional for the particular playing group.

edit 2: Better formatting

edit 3: Forgot about Concentration! Creo and Perdo magic are technically permanent, while the other three techniques (Muto, Rego, Intellego) are technically temporary (according to my understanding of Ars Magica, which isn't extensive). Therefore I ruled in my game that a Mage could not cast another spell while maintaining the effects of a Muto, Rego or Intellego spell. This depends on the situation however, and it really is up to the GM how it applies. For instance Rego Aquam to divert a river would probably be permanent, while Rego Mentem to control another's mind would be temporary.

edit 4: Might as well add the source material. Ars Magica 5th Edition is owned by Atlas Games (previously owned by White Wolf and Wizards of the Coast) who also produced "Once upon a Time" (absolutely love that card game). Lasers & Feelings is by One Seven Design and is a sci-fi rpg that is a blast to play.

edit 5: Minor problems with the mod bot