Better rules for Invisibility?

[Donny Brook]

Whenever it comes up in a game, I find myself dissatisfied with two things about Invisibility.

1. Affects Machines. If I am invisible to the band of light that a machine uses, how the heck can it see me? Why do I need this enhancement?

2. Why is it the opposite of every other advantage being set as default Always On. Every time I try to put this on a character I have to get my head around this backwardness.

Suggestions anyone?

[Stormcrow]

Originally Posted by Donny Brook

1. Affects Machines. If I am invisible to the band of light that a machine uses, how the heck can it see me? Why do I need this enhancement?

I take this to mean that the basic advantage makes you imperceptible rather than actually affecting light rays. Actual invisibility costs more.

2. Why is it the opposite of every other advantage being set as default Always On.

The basic advantage models naturally invisible creatures, of which there are many. Being able to switch invisibility on and off costs more.

Put simply, I don't think a character who can become invisible at will is the base concept of Invisibility.

[Donny Brook]

Originally Posted by Stormcrow

I take this to mean that the basic advantage makes you imperceptible rather than actually affecting light rays. Actual invisibility costs more.

However, that approach is undermined by wording in the advantage text:

"Invisibility only works against one
sort of vision. Types include electromagnetic
vision (which encompasses
ordinary vision, Infravision, Ultravision,
and radar), sonar, magnetic
fields, and anything else the GM
comes up with. If you are invisible to
electromagnetic vision, you do not
cast a shadow and don’t show up in
mirrors."

The basic advantage models naturally invisible creatures, of which there are many. Being able to switch invisibility on and off costs more.
Put simply, I don't think a character who can become invisible at will is the base concept of Invisibility.

You might be right on that, but honestly, I'm kind of stumped on what invisible creatures it might have been intended for.

[dcarson]

Originally Posted by Donny Brook

You might be right on that, but honestly, I'm kind of stumped on what invisible creatures it might have been intended for.

The classic source is The Invisible Man who had the problem of being stuck invisible.

[David Johnston2]

Originally Posted by Donny Brook

You might be right on that, but honestly, I'm kind of stumped on what invisible creatures it might have been intended for.

Ghosts. It's intended for ghosts. Thus, cameras can take pictures of you even though you ar invisible.

[Not another shrubbery]

I always figured that the model for GURPS Invisibility was The Invisible Man, or perhaps Wylie's lesser known The Murderer Invisible. Stormcrow's suggestion to think of the base advantage as affecting perception rather than how light interacts with you is reasonable. Both Griffin and Carpenter would probably have Affects Machines (though it wouldn't be of use to Griffin and only minimally so to Carpenter) as their invisibility was from changing the refractive index of the body to be equal to the air around them.

The obvious solution is to just build those Special Enhancements into the base price of your version. Since that comes to 64, you could give them a perk (say, having a suit of clothes that becomes invisible also) and bump the cost to 65.

[Anaraxes]

Originally Posted by David Johnston2

Ghosts. It's intended for ghosts.

This. It's a supernatural feature, not based on anything as mundane as a physical rule about bending light rays.

The Advantage mechanics also suffer a bit from the downside of the often-desired design strategy of having only minimal modular base components that you can build other things out of -- in this case, if you line up commonly-seen fictional flavors of relative imperviousness to detection by man or machine into one base with modifiers, and call that base "Invisibility", it might well need a bunch of modifiers to build up to the state someone thinks of if you use the word "invisibility". (That's why the GURPS designers originally came up with a hodgepodge of different amount so of bundling, sometimes adding and sometimes subtracting with modifiers. They weren't designed to some abstract theoretical definition of elegance; they were trying to make it easy to build characters by grabbing pre-bundled effects into one common name. Any way you choose to design traits, someone thinking another way is going to object.)

Buy the effects, not the name. The mechanics are what they are. Trying to make "logical" guesses based only on the title of the paragraph is just going to lead to sadness, tripping all over the fact that sometimes Advantages are big lumps of related stuff, other times little building blocks and starting points.

[Stormcrow]

Originally Posted by Donny Brook

However, that approach is undermined by wording in the advantage text:

"Invisibility only works against one sort of vision. Types include electromagnetic vision (which encompasses ordinary vision, Infravision, Ultravision, and radar), sonar, magnetic fields, and anything else the GM comes up with. If you are invisible to electromagnetic vision, you do not cast a shadow and don’t show up in mirrors."

It still doesn't say anything about affecting the light reflecting off of you, only that Invisibility works against one sort of "vision." If it works against your vision, that's a case that it affects your perception of light, not the light itself.

But I wouldn't get too hung up on the exact wording. The effects are clear.

[aesir23]

This is an easy fix:

Change the cost of invisibility to 65. It automatically effects machines and is switchable.

Create the following Limitations: Not Against Machines - 30% and Not Switchable -10%.

I did some rounding to satisfy pentaphilia, but it keeps the prices close enough to raw that it doesn't matter.

Raw: Invisibility (not Switchable, not Machines) =40, (Switchable, Not Machines) = 44, (Machines, Not Switchable) = 60, (Switchable and Machines) =64.

This Hack: Invisibility (not Switchable, not Machines) =39, (Switchable, Not Machines) = 46, (Machines, Not Switchable) = 59, (Switchable and Machines) =65.

[dataweaver]

This. Also, a related hack that I'd make would be to double the cost of Insubstantial, and replace the +100% Affects Substantial Enhancement with a -50% Doesn't Affect Substantial Limitation.