This game will be run with a combination of 3rd and 4th edition rules, leaning heavily toward 4th edition, if only because we can get more copies of that book and it has a useable index. And, of course, all of it's altered to fit modern-day scenarios. Don't panic--you'll catch on.
Simple, Stress, and Quality die rolls are preserved. Botches, etc., are still around. The basic "roll-and-add-appropriate-stats-and-skills-to-beat-an-Ease-Factor" system remains pretty much intact. Something to note here, which is unclear in the rules: when rolling a stress die, and a zero results, you roll a number of Botch dice. However, even if you are fortunate enough to not Botch, the roll is still Zeroed Out. Zeroing Out means that all internally-based factors are ignored and assumed to total zero; external factors are still added/subtracted from the total. Internal factors are essentially Characteristics and Ability scores. External factors include such things as Aura bonuses/penalties, Roleplaying bonuses, weapon and armor stats, etc. These rules cut down on the chances for someone to roll a "Zero" and still succeed in the action. While this is still possible, remember that rolling a "Zero" means that something won't go quite the way you expect it to, even though you may technically have accomplished your goal.
Example: You hear a burglar downstairs and you decide to sneak up and deck him with your trusty Louisville Slugger. Everything is going fine as far as stealth rolls, and so on, are concerned. Then you actually swing, at which point you roll a zero. Botch dice are rolled, and there's no botch, but you've zeroed out. You've got lots of bonuses going for you (attacking from surprise, behind, in your own living room, in the dark with a big club, etc.) so you hit anyway, and hopefully, that hit took him down, because there's an awful cracking sound as the bat breaks in two on the back of the burglar's skull.
There won't be actual Troupe Play (i.e., everyone rolls up a Magus, Companion, and a Grog). Three characters per person can get awfully unwieldy for all concerned, especially when one's characters are expected to interact. Therefore, to avoid schitzoid conversations, everyone will get one character as in a standard RPG, either a "Magus" or a "Companion."
The distinction between the two character tipes are not hard and fast in this campaign. The only difference is that a Magus-type character will have well-defined magical abilities, whereas a Companion-style will tend not to. This doesn't mean that your Companion can't work magic, just that it doesn't follow the "normal" game conventions for mages. This may mean that he or she is non-magical, or simply has a few magic-like powers (bought as Virtues), or is a "hedge wizard," or is perhaps something completely different.
In normal Ars Magica, the game is slanted, character-wise, toward the mage. Here, if you choose a Companion type, you will be compensated. Character generation will be as equal as possible between the two categories.
Still, it may seem as you read this that anyone who can wield magic in today's society must be very powerful. True, but there are limits. Bear in mind that Magical Auras are virtually nonexistent, many spell components and vis are extremely scarce, and that there are always other, more powerful entities and groups out there. Anyone blatantly abusing their power is bound to be noticed--and dealt with--by someone who objects to their methods or perhaps simply doesn't want a future rival as they use similar methods. Even a puny mundane can pack quite a wallop when he or she is wielding the right modern technology ("You go ahead with the chanting and waving your arms. I'll unload my AK-47 in your general direction.").
Continue: Virtues and Flaws