A game with fewer rules?

Let me start by saying that the Ars Magica setting is so much better than anything I have seen sine I started playing rpgs. I want to play this game.

At the same time, the amount of rules, the long additions of boni detract from telling stories
A lab explosion can be fascinating but

Creo 12 + Corpus 11 + mt 5 + specialization 1 + aura 4 + focus 11 + cyclic magic 3 + inventive genius 3 + shape boni 6

That isn’t roleplaying - it only leads to people staring at numbers, because if you don’t, some guy (usually male) will swoop down and munchkin away any meaningful interaction.

Which takes me to my second point. The system has exploits, like mastered PeVi that can kill many challenges, and has random factors for abilities that are so high that attributes and dice are more important than skills - an extraordinary competent apprentice weaver has

Skill 2 + attribute 4, which is almost as good as a master, skills 6 + attribute 2: about 20% likelihood that the master beats the apprentice.

So is there a conversion of Ars Magica to FATE that works?
If there isn’t, how would one convert it?

For a game in the perfect setting, with the perfect rules.

PS: please don’t reply and say that you like the rules as they are. I am looking for people who do not like the rules and are willing to work towards a conversion into a real roleplaying game. For those who like the rules, there are hundreds of other threads on this forum.


It would help to know what features of Ars Magica you want to preserve ... lab system? spontaneous magic? Mythic Europe? covenants? long term advancement in general? troupe style?

Have you considered playing 3ed? Sure, that has its problems, but in many ways it is considerably simpler, and it certainly has fewer rules supplements to bog you down.

What do you think of Mage and WorldTree for comparison? Both have flexible/spontaneous magic, even if they are very different. The comparison would tell us something about what needs to be converted and what can be sacrificed.

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I have half a conversion for fate, as I love fate dearly, but I shelved it due to assuming an utter incompatibility of player base

Here is an olden thread that discussed building a FATE-ArM hybrid at some length.

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There is a Fate Core based wizard game that I've been told is very similar to Ars Magica, called Magonomia (Drivethru link). The big difference being that its default start point takes place during the Renaissance, rather than 1220. One of the writers for it is, in fact, my favorite writer for Ars Magica, Timothy Ferguson, who writes some supplementary stuff for Magonomia on their blog.


Magonomia is an excellent game of wizards in a historical setting. It also takes care to explain how certain FATE mechanics work in the game, making it one of the easier-to-learn FATE derivatives.

If I was adapting Ars to a rules-light system, I think Heroquest (as used in Heroquest: Glorantha, don't know if there are any other offical settings for it) would work well for a narrative game of magic in a fantastic medieval world, but its inbuilt mechanisms for scaling threats would make it feel somewhat different from Ars.

As always, the crucial question is "What makes for a great Ars Magica experience?" and try to make sure you keep as much of that as possible.

I will read magonomia and see if it helps. Thanks! I’ll share my impression once I have read it.

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Neat thread. I'd like to see a more rules-light version of ArM, too. I tried to make one, but I found it rather difficult.

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I wonder how hard this has to be. No doubt it could be hard, if we make high demands, but there are a lot of simple changes to make a lot of difference.

  1. Rules complexity. Supplements make the main culprit. We could scrap them all.
    • Realm of Power characters would have to be made fiat from core examples, as we did in 3ed
    • The Mysteries is lost, possibly making the mystery cult houses less interesting to play, but they are supposed to work just from core rules too. An acceptable loss, I think.
    • Other supplements are probably less controversial to lose.
  2. Lab total complexity. We could seriously prune the list of virtues and flaws to reduce the number of modifiers. The lab improvements from Covenants were already scrapped above.
  3. Relative weighting of dice. I am not convinced that this is so much of an issue, but if it is, could we use a D6 instead of a D10?
  4. Relative weighting of characteristics. This has bothered me too. Characteristics have a range of 10 (±5) while abilities typically stay within 8 except for very mature characters. We could
    • change all abilities to arts progression, adjusting ease factors correspondingly. (One might have to change the die (say D20) in the combat system to get enough randomness, but that is possible too.)
    • simply reduce the range of characteristics. Scrapping virtues and flaws completely would reduce it to ±3.
  5. More on mechanical complexity. We could even scrap such things as aura bonuses/maluses. Arguably harsh, but it removes a term in calculations.

It seems to me that except for the die/characteristics/ability balance, there is nothing to be gained by moving to a different base system. The problem is the number of narrative elements that are given a mechanical impact, and even the balance issue can be resolved with relatively simple tweaks to the existing system.

How does this compare to your conerns, @Pralix ?

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I definitely agree with 1, although something should be brought in to replace the lost pie of the mystery houses. Because without house mysteries, they kind of suck.

I think that 3 (less random dice) and 4 (more random dice) are mutually exclusive. Trimming down the game should not mean needing a host of different dices, but ideally, just one size.

Aura bonus/malus could just become a ternary thing. Roll 2d10 pick the worst (malus) or best (bonus). Neutral being just a simple roll.

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To clarify what I meant. It was OP he thought the dice overshadowed skill. I see that they have a point when it comes to ability checks, but I think combat and magic is as random as it should be. Thus (3) addresses OP's concern. MMMV.

In (4) I suggest expanding the range of ability scores, which would make the die less important than it is. IMO that makes magic and combat too predictable, something we may compensate by using a D20 instead, or just have one side roll if your prefer. OPMMV

So, yes, they may be mutually exclusive, but there are a few design questions which needs to be discussed in detail before a complete design proposal can be made. In particular, we need to note that the die roll is more random against an ease factor than it is against an opposing roll. Mathematically +D10 has higher entropy than a difference D10-D10.

I have sympathy with that viewpoint, but we should remember that we enjoyed 3ed and 4ed for a long time. Mystery Cult Houses only became a thing in 5ed.

Compared to current situation? Certainly. Compared to the other Houses? Not really, if you also get rid of the Mystery Cults and the initiation mechanics as well.

The introduction of the Mystery initiations in 5th edition led to a major increase in both complexity and power level, IMHO.

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Ars Magica can of course have fewer rules if you simply ignore the rules you find get in the way, which is what I do. You can certainly ignore all the supplements if you want to. The core ability rules are pretty simple, as is casting a formulaic spell. Spontaneous magic as written can take a bit more thought, but as long as you count everything written as rough guidelines and are prepared to make things up as you go along, it shouldn't slow you down much. The laboratory rules and long term events rules cover long term activities that occur outside of the focus of actual role-playing sessions. Part of the attraction of Ars Magica is that it provides a structure for these activities that most RPGs don't. I don't think a game like Fate could easily handle this. If you are only interested in role-playing in the here and now they could also be largely ignored, except perhaps for character advancement which most players don't want to lose.

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No, that isnt roleplaying - that is used if someone don't do roleplaying. He just do Labwork. Adventures comes form a GM, roleplaying from the group (and the GM), and Labwork should only be done outside gaming sessions - at least for me. ars magica is a pnp rpg with focus on magic, not numbers.

The problem for me isn't the supplements but rather the core rules, and in the core rules it's the core mechanics. There is an XP in addition to Score, there are spell magnitudes in addition to spell levels, there are countless modifiers and high numbers, there is division... way too much arithmetic.

To simplify ArM, I would suggest something along the following:

  • Scrap XP. Instead, use Ability/Art scores only and a chance to advance them, a la Third Edition.
  • Scrap spell levels. Instead, denote spells by their Magnitude only.
  • Scrap individual spell guidelines. Instead, use a general spell guidelines table, with TeFo combinations given as EXAMPLES of how that general list plays-out for each combo. Yes, like Third Edition again.
  • Probably ditch the (very nice!) RDT system, and go instead with Third Edition's "appropriate range, duration, and target" for the effect/spell idea.
  • Lower Art levels, so that each increase is meaningful and corresponds to about a +5 increase currently. This is required to be consistent with dropping spell levels.
  • Use 1dF for rolls.
  • Special circumstances such as Virtues, Auras, and so on may add +1, more in rare cases.

For example: a starting character might have a score of 2 in Creo and Ignem (corresponding to level 10 in 5e), and a Magic Focus in fire magic. If the player wants to cast a fire spell, he rolls 1dF+2 Creo +2 Ignem +1 Focus, for an average spell of 5th magnitude, but possibly getting 4th or 6th. Confidence or Fatigue can add +1.

Oh, and

  • Spontaneous magic done with -2 (corresponding to -10 in 5e) to the roll, not division by 2. No divisions! This isn't Ars Mathematica! As few substractions as possible, too. Yes, addition is easier, and small numbers are easier.

Oh, and combat definitely needs an yet-another overhaul for simplicity and uniformity too. Perhaps...

  • Roll initiative, every character gets one action which is opposed by a passive-Defense (i.e. no-roll). Spells are opposed by a Dodge (aimed spells) or by a Magic Resistance (Parma). Attacks from weapons may be opposed by Dodge or Weapon Skill. Damage from weapons or spells must pass Defense + Soak; Grogs are Incapacitated by 1 past Defense+Soak, Companions and Magi Incapactiated by 5 hits (add up numbers past Defense+Soak, accumulating from multiple attacks. Possibly a Wound (-1 penalty) to all rolls and Defense per hit?). Another hit or an excess of 2 kills instead of incapacitates. Size adds extra hits.

I could go on, but ... well, something along these lines. :slight_smile: Sorry, haven't house-ruled for a while.... :smiley:


Oh, thanks for the praise!

The game has some other Ars authors in it too. Basically it's Andrew Gronosky from Hedge Magic plus a decade of musing.

The big difference is it's a lot more urban No Dominion and lower fantasy