Gadutan-755, or simply Tracer Fluid, is a radioisotope tracer fluid for use in radiobiological medical scans.


Gadutan-755 is a cloudy, pale-orange radioactive tracer fluid that was distributed by PACE Laboratories and Saint Mary Hospital presumably to patients about to undergo any type of radiobiological scans to help improve scan image clarity. It contains a mixture of Gallium, Gadolinium, and an element presumably only to be know in the future with the atomic symbol Unbt-42.


At the beginning of the game, David Munshi calls Simon Jarrett to remind him to drink the Tracer Fluid before the scan so that they can get a better image. Simon then proceeds to find and drink the entirety of the bottle of fluid before taking off to the scan center. He describes it as "feeling like milk, but it tastes like sucking on a penny". The Tracer Fluid's taste might actually be accurate, seeing how the tracer fluid is composed of multiple heavy metals.

Behind the Scenes

  • Gadolinium is an actual contrast agent used with MRI scans.
  • A closer look at the bottle label reveals that Unbt-42 might actually be Unonbutanium; a completely fictitious element, since butane isn't an element: it's a molecular compound.
  • On the bottom right hand corner, the designation F78 can be seen. This might be in reference to the U.S. ICD10 Diagnosis code: ICD-10-CM F78, which defines as "Organic disturbances and intellectual disability.". The probability that this was placed on the bottle label intentionally by the developers isn't unlikely, since Canada and the US share many legal codes and restrictions. This further supports the claim that the "human" Simon had brain damage after the crash that killed Simon's colleague, Ashley Hall.



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