Got to talking the other day about invisibility and how it is handled, mechanically, in various game systems. Notable in this discussion was just how neutered the invisibility spell was in every edition of D&D we’d ever played, and in fact I’ve yet to find an edition or clone that doesn’t have effectively the same wording – that you stay invisible until you attack. Pathfinder, the closest I get to D&D anymore, gets very specific about what constitutes an attack (it includes spellcasting, including area of effect spells, but does not include, say, cutting the ropes on a bridge someone is using, causing them to fall to their death) but regardless this has been true at least as far back as Holmes Basic, and I’ve seen references to OD&D and Chainmail using the same system.
Someone was concerned that invisibility was a little too powerful, it would seem.
But what of GURPS? I thought about it, and I couldn’t recall a time that a PC had used any sort of invisibility magic in any campaign I’d participated in. Notably, we have had NPCs become invisible (a minotaur in the first instance, nearly killing us all, and a slaver bandit with a potion in the second case) and I knew the effects weren’t nearly so curtailed.
The spell as presented in the default magic system in GURPS is very straight forward, explained in a single paragraph:
The subject cannot be seen and does not appear in reflections or photographs. He still makes sounds and can be tracked by scent or footprints. Anything he picks up becomes invisible, unless he wills it to stay visible. Infravision cannot detect him, but See Invisible can. Invisible characters have a great advantage in combat: see p. B394.
Duration: 1 minute.
Cost: 5 to cast. 3 to maintain.
Time to cast: 3 seconds.
Prerequisites: Six Light spells,including Blur.
The emphasized portion is key here – the concept of invisibility is standard in GURPS, as it could come about any number of ways, the mixed blessing of a universal system. Of note here is that the spell isn’t instantaneous – it takes a few seconds to work up to it; it’s not cheap, and even an expert caster (with Invisibility at skill 20) invests 3 FP to cast the spell and 1 more every minute to maintain it; and it’s not something you can just take as your first spell, needing a fair handful of prerequisites.
What does GURPS say on B394 about combat with invisible people? Perhaps unsurprisingly given a system which lavishes so much detail on everything, the answer is nuanced:
A combat situation where some fighters can’t see their foes affects attacks and defenses.
Attacker cannot see anything. If the attacker is blind or in total darkness, he can make a Hearing-2 roll – or use some other method – to discover his foe’s location. If he fails his Hearing roll, he may attack in a randomly chosen direction (on a map, he must specify the hex). He attacks at -10 (-6 if he is accustomed to being blind). Roll hit location randomly.
Attacker cannot see his foe, but can see his other surroundings. If only the attacker’s foe is invisible, use the rules above, but the attack penalty is only -6.
Attacker cannot see his foe, but knows his location for sure. If the foe is in a single smoke-filled hex or the like, use the rules above, but no Hearing roll is required and the attack penalty is only -4.
Defender cannot see his attacker. If the attacker (including his weapon) is invisible but the defender is aware that he is being attacked, he may dodge at -4. If the defender makes a Hearing-2 roll, he may also parry or block – still at -4. If he is completely unaware of his attacker, he gets no defense at all! If the attacker is in smoke or unnatural darkness, but the defender is not, he defends normally, since he can see the weapon coming.
Note also that an unseen fighter can safely try things that a normal fighter could never do – or he may just wait in a corner until his foe is exhausted!
All part of a unified system, but handled in such a way as to be realistic and brave enough to allow invisibility to maintain some of its magic. It’s still not an “instant win” button, but it does allow for duels with invisible swordsmen, wrestling with unseen assassins and other such awesomeness.