Magic Gadget question

[SilvercatMoonpaw]

I'm trying to stat a magic item that lets users transform into a single kind of aquatic creature. Once they do, even removing the item from their person doesn't change them back, and it can't be dispelled.

I'm still a little confused as to how GURPS would do this: Is this simply Alternate Form with Can Be Stolen? Or do I need to use a different Advantage to model how this item works?

[Rolando]

It is Alternate Form with whatever gadget limitation you want to add.

After the transformation the gadget is not needed though, the gadget may be necessary to transform back though, as Alternate Form doesn't have a duration limit you can stay transformed until you fall unconscious or sleeps. With the Modifier Once On, Stays On from Power the alternate form will be permanent until the gadget is recuperated to be able to return to the original shape.

The reaso I see you need the gadget to return to the original shape is because you need the advantage to turn it on or off. No gadget means no advantage to turn off.

You may also use Absorptive modifier to absorb the gadget once transformed so you retain the advantage and are able to turn it off whenever you want, but still need the gadget to transform in the first place.

[SilvercatMoonpaw]

Originally Posted by Rolando

After the transformation the gadget is not needed though, the gadget may be necessary to transform back though, as Alternate Form doesn't have a duration limit you can stay transformed until you fall unconscious or sleeps. With the Modifier Once On, Stays On from Power the alternate form will be permanent until the gadget is recuperated to be able to return to the original shape.

Okay, thank you: this was the part I wasn't sure about.

[Stormcrow]

Note that you would only stat this as an item with character traits if you're planning on making it part of a character's sheet, paid for with their own points. If it's just an item they find and use one or twice, and never becomes a part of their character, you don't need to work out the details of the Alternate Form. Just declare that the device swaps in the alternate racial template and works however you like.

[SilvercatMoonpaw]

Originally Posted by Stormcrow

Note that you would only stat this as an item with character traits if you're planning on making it part of a character's sheet, paid for with their own points.

I'm making it part of a racial template. I know that's not usually how those are supposed to work, but it's part of the race's identity at this point in my thinking, so it's easier to have and remove that not have and need to put in.

[Varyon]

Originally Posted by SilvercatMoonpaw

I'm making it part of a racial template. I know that's not usually how those are supposed to work, but it's part of the race's identity at this point in my thinking, so it's easier to have and remove that not have and need to put in.

A Gadget that's necessary to shapeshift would be entirely appropriate for a Selkie, which it sounds like is more-or-less what you're trying to make. In fact, looking at the entry in the GURPS wiki, that's exactly how they were made in GURPS Fantasy (the first entry is a bioroid from GURPS Bio-Tech, scroll down for the Fantasy interpretation).

[Plane]

Originally Posted by Varyon

A Gadget that's necessary to shapeshift would be entirely appropriate for a Selkie
..
that's exactly how they were made in GURPS Fantasy

F110 notably uses a "skinbound" note for Shapeshifting, which F209 talks about in the section "Skin-Turners". It cites F131 where it notes that gadget limitations are half-cost if you don't need to use the gadget to change back (ie you're wearing the skin when transformed).

The note is "absorbed into your body in the process; or you take off the skin of your base form".

Selkies are the latter case (since their base form is a seal, their alternate form is human) since they "remove his skin and turn into a man"

Werewolves OTOH tend to be the former case (a man who puts on a wolf skin to become a wolf)

If you needed the gadget to go in both directions it'd be a full discount instead of half.