Guppy's Collar's effect is possibly a subtle reference to Schrōdinger's Cat; a thought experiment deconstructing the Copenhagen interpretation on quantum mechanics, in which the titular, (nonexistent) cat is placed in a sealed box, with a mechanism intended to kill or spare the cat depending on the behavior of an atom. According to the Copenhagen interpretation, the cat would be both alive and dead, simultaneously, until an individual viewing the contents of the box 'collapsed' reality into one or the other outcome.
97.89.112.92 07:28, 6 December 2014 (UTC)
Does luck affect the chance for Guppy's Collar to activate? If it does, that would be something very interesting to note in its page.--67.172.166.241 09:13, 1 January 2015 (UTC)
Na, it has been said by Ed that it's 50% chance of revival.
--Dooomspeaker (talk) 10:27, 1 January 2015 (UTC)
I was playing recently and got both the ankh and the collar. When I died the ankh activated before the collar, so I'm changing the text on the main post to match this. I may be wrong since the ankh transforms you into ???
- The collar only has a 50% chance to activate, so if you transformed into ???, that doesn't necessarily mean the ankh takes priority over the collar. --Exschwasion (talk) 03:37, 2 February 2016 (UTC)
keeper glitch[]
I just had a weird experience, where I was revived with half a soul heart... while playing as the Keeper! Here's the seed if someone wants to research it: 36GK WXFK
Here's how it happened: I was in chapter 3 on Depths/Necropolis (don't remember which) as Keeper and I got to the devil room, where Guppy's Collar and Multidimensional Baby were offered to me for one heart each. There were fireplaces and one of them gave me a penny. I thought "Great, now I can take both devil deals without dying!", not knowing that I need a health up item to restore my second health coin (I just unlocked Keeper, don't judge). So yeah, I take Guppy's collar first, get the penny and then Multidimensional Baby and of course I die. I got lucky and got resurrected but I had half a soul heart. I couldn't tell if I was still playing as the Keeper, I thought maybe I got resurrected as a different character similair to Lazarus' Rags or Judas' Shadow, but I had tons of items that changed Keeper's appearance completely. So I quit the game to see on the continue screen if I was still the Keeper. The game still saw me as the Keeper and when I continued the run, I had no health and died immediatly.
In addition to that, when I used the restart button, I started as Isaac instead of the Keeper.
keeper glitch[]
Wasn't really sure how to post this so I just added it to the one already here.
As stated above except I kept playing. I was offered guppys tail and collar so i took both and was revived with half a soul heart. Afterwards I could take as many devil deals as I wanted without loosing the soul heart. When picking up red heart items such as milk it restored one health in the form of a "coin heart". Picking up another red heart item gave me another "coin heart" and removed the half soul heart. I stopped taking devil deal items after loosing the soul heart (I wanted to see what would happen when I finished the run), but even when I had one coin heart and half a soul heart, I could continue to take devil room items without loosing the half soul heart.
Upon completion of the run it did counted as a keeper run.