GURPSよろず

see p. B62
Beings largely unaffected by the physical world appear in myth and fiction at least as often as those that can fly. Paradoxically, most such entities can “anchor” themselves to material objects as needed, allowing them to stand on floors, ride in vehicles, and so on. This is a standard feature of 「非実体化」. What the insubstantial form looks like, and the things that can impede it, vary with the origin of the trait:

Dimensional:
　The traveler transports himself into a dimension parallel to the physical world. He looks slightly transparent, as if he weren’t all there. Any place in the ordinary world that lacks an equivalent location in the other plane is completely off limits.
Individuals with dimension-traveling foes often build strongholds in such locales!

Divine:
　This represents the ability to assume a “god form” that can roam the mortal world at will. The cleric looks normal except for the addition of something symbolic of his patron; e.g., a wreath of flame, for the Fire God. He can’t infiltrate places of no or low sanctity, however; see Special Rules for Divine Powers (p. 175).

Elemental:
　The user turns into electricity or light, or vibrates at a weird frequency. He becomes a man-shaped glow, visible shimmering, etc., as befits his element. He can’t penetrate barriers that are proof against his element; e.g., a grounded metal cage would exclude an electrical “ghost.” Superscience force fields often block such 「非実体化」.

Magical, Psionic, or Spirit:
　The user enters the ethereal, astral, or spirit realm (these might be the same or quite distinct, depending on the setting).
His appearance is misty and ghostly, and possibly luminous or shadowy. Shamans with spirit powers often look like beasts. Spells, psi abilities, and sorcerous rituals that obstruct spirits also block this ability.

■代替案（Alternatives）
Both 「超感覚」 (Projection, +140%) and 「非実体化」 (Affect Substantial, +100%; Projection, -50%) cost 120 points. They’re comparable, but there are important differences.
Notably, 「超感覚」 gives an invisible form with a 10-yard range limit from the body, while 「非実体化」 gives a visible form with no range limit.
To represent partial solidity, use 「負傷耐性」 (「集合体」) (p. 52) or 「影の体」 (p. 73). To be able to pass through just one substance, take 「[物質透過]]」 (p. 66).
「非実体化」 doesn’t include invisibility. For that, take 「透明」 (below), too --possibly with Substantial Only. 「非実体化」 does include total silence, though, save when you choose to speak. You’re undetectable to hearing, and need only make 忍び rolls if there’s a chance you’ll be seen.

■追加特別限定（New Special Limitation）s
No Vertical Move:
　You can’t disregard gravity. You must move across a horizontal surface, or along a slope that wouldn’t require 登攀 rolls.
You still weigh nothing, so you don’t leave footprints and can walk on surfaces that wouldn’t support a solid body, such as the surface of a body of water. -10%.

Noisy:
　You aren’t silent. You make noises equivalent to footfalls when moving and breathing at all times, and are no harder to hear than an ordinary human. -5%.

Projection:
　Your body doesn’t become insubstantial. Instead, it falls unconscious and you step out of it in insubstantial form. Like someone using unmodified 「非実体化」, you’re visible and present, making you subject to anything that affects insubstantial entities . . . while your body remains in the physical world, vulnerable to material threats; see Projection (p. 44). You can’t use spells, psi abilities, etc. in this form unless you also take Affect Substantial. -50%.

■パワーアップ（Powering Up）
This ability suits almost any kind of supernatural or elemental power, as noted above. With the Projection limitation, it’s especially suitable for Astral Projection. 才能 adds to any roll required to “push through” a resistible barrier or use 「非実体化」 for a Power Dodge (see p. 167).