What Counts as an Attack for Purposes of Wrecking Invisibility in DFRPG?

In traditional D&D, the Invisibility spell went away if you attacked.  So it gave you one sneak attack, but not ongoing sneak attacks.  And there was sometimes also a higher-level version called Greater or Improved Invisibility that stuck around if you attacked.

In GURPS Magic, the Invisibility spell didn't go away if you attacked.  It was quite good, but also quite expensive.

One of the changes for Dungeon Fantasy and later DFRPG was making Invisibility go away if you attacked, but lowering the mana cost a bit to compensate.  The wording in DF1: Adventurers is "To keep Invisibility from completely upstaging thieves, the spell ends instantly if the subject attacks, casts a combat spell, or otherwise does anything more violent than moving around, spying, and stealing. Reduce energy cost from 5/3 to 4/2 to compensate."  This wording is reused almost verbatim in DFRPG: Spells.  So it's clear that violence ends the spell, but not exactly clear what counts as an attack.

A D&D 3.5 SRD goes into a bit more detail.  "For purposes of this spell, an attack includes any spell targeting a foe or whose area or effect includes a foe. (Exactly who is a foe depends on the invisible character’s perceptions.) Actions directed at unattended objects do not break the spell. Causing harm indirectly is not an attack. Thus, an invisible being can open doors, talk, eat, climb stairs, summon monsters and have them attack, cut the ropes holding a rope bridge while enemies are on the bridge, remotely trigger traps, open a portcullis to release attack dogs, and so forth. If the subject attacks directly, however, it immediately becomes visible along with all its gear. Spells such as bless that specifically affect allies but not foes are not attacks for this purpose, even when they include foes in their area."

(Of course D&D rules are not in play in a DFRPG game, but it's an example of someone thinking about the problem and writing more clarifying text.)

In our DFRPG game, I ruled that Rapier Wit counted as an attack.  It's an attempt to directly stun an opponent, and I think that the effect is more important than the mechanism here.  I see Rapier Wit as a whole lot like the Kiai ability that Martial Artists can have (which explicitly says it counts as an attack), or the Stun spell (which is obviously an attack spell since it's targeted on an opponent and nerfs them.)  I think Rapier Wit is an easy call.

The hard calls for me are the cases like pickpocketing an enemy, tying his shoelaces together, or cutting a rope bridge with enemies on it.  The DFRPG spell text explicitly allows stealing, so I decided pickpocketing is okay.  I think tying an enemy's shoelaces together in a combat situation is a grapple attack, so that makes you visible.  The D&D SRD uses the rope bridge as an example that doesn't make you visible, but I think they got that wrong.  It's an attack at a distance, but it's an attack.  Similarly, magically moving a heavy object over someone's head and then letting it fall is an attack, in my mind.

The other interesting case is area spells designed to affect enemies later, rather than now.  I think casting Glue in an enemy's current hex is obviously an attack.  But what about casting Glue in an unoccupied hex that an enemy might or might not step in later?  I think I'll allow that one, though it's a very edgy case.

(Of course these are just local rulings for games where I am the GM; I don't have any authority to tell anyone else how it should work in their games.)

The moral of the story is that RPG rules are never 100% clear, the GM on the spot always has to make a call, and players have to deal with it.  All the GM can promise is to try to be consistent and fair.  There are games that claim to be "100% Rules As Written," but that just promises a lack of deliberate rule changes.  The GM still has to fill in the gaps when the rules aren't perfectly clear, which is often.