Blue enzymes are one of three types of enzymes seen throughout the games Test Subject Blue, Test Subject Green, and Test Subject Complete. They also appear in the spinoff, Test Subject Arena.

General appearance

Blue enzymes appear as small drops of a goo-like substance. The drop spikes at the top, which makes the enzyme shaped similarly to a water droplet; there is very little shading on the enzyme.

Game information


Test Subject Blue

The scientist at Xeno Industries made a blue enzyme, then placed it in a proto-suit and ran it through tests to measure its intelligence and capabilities.

Test Subject Green

Eventually, Doctor Nastidious stole the blue enzyme (along with the other enzymes) and used it in his own tests before placing it in a new suit, Rex209.

Test Subject Complete

Nastidious discovered that the formula to create blue enzymes was incomplete, so he returned to Xeno Industries to find the complete formula. It turned out the formula wasn't at the lab.

Rex209 eventually discovers a file within its own hard drive concerning Serum BLUE1207, uncovering the truth about the blue enzyme — it was the essence of life. The blue enzyme sacrificed itself to revive the scientist from death.


There are only two known blue enzymes the Professor and Doctor Nastidious used.

The first was combined with an orange enzyme, making Green.

The second is the main character, Blue.

Test Subject Blue

Main article: Blue

Test Subject Blue is a blue enzyme made by the scientist at Xeno Industries. After creating it, the scientist ran it through tests to test its reflexes. To his surprise, the scientist found that it was smart.

It could skillfully complete the tests and defend itself. The scientist nicknamed this enzyme Blue.

After successfully completing twenty-five tests, the scientist merged the blue enzyme with an orange enzyme, creating a green enzyme which the Scientist also used. The scientist used the blue enzyme for all other tests he did.

Blue enzyme bullets

Blue enzyme bullets are similar to the orange enzyme bullets, but are blue. It is shot by proto-suit Blue. The bullet dies when they kill an orange, green or even blue enzyme or even when they touch anything.