Mimic green enzymes are the smartest and probably most dangerous enemy in the Test Subject series. Mimic green enzymes have a variety of appearances; their most recognized appearance being a green coloured Proto-Suit with eyes.
The enzyme first appears as a green blob, which will turn into a green proto-suit, if Blue is spotted. When this happens, the enzyme turns into an exclamation sign, and then takes the shape of the proto-suit.
The green proto-suit has the same shape as the player, but it has two small black eyes in the middle. The exclamation shape has a green enzyme circle and under it, and long green enzyme that levitates in the air.
Mimic green enzymes appear only four times throughout the game Test Subject Green, first appearing on level 16. In three of the four levels, mimic green enzymes are spawned out of a flip door whenever another mimic green enzyme is killed or successfully kills Blue. Mimic green enzymes appear in a wave like shape, moving across the platform and reversing direction once the end or a wall is met, which make them similar to crawling green enzymes.
If Blue lands on the platform a mimic green enzyme in wave form is on, once Blue gets in range of the green enzyme, it will transform into an exclamation mark then back into its wave form. It will also transform into an exclamation mark whenever Blue shoots at it. Sometimes it will transform into a green dodge orange enzyme moving its body up to avoid Blue's proton bullet.
Once the mimic green enzyme's wave appearance gets in range of Blue, it will transform into a green version of Blue's Proto-Suit and mimic all movements Blue has done. If Blue shoots at it when the Green Enzyme is facing him, it will transform into a green shield orange enzyme, blocking the proton bullet. A second consecutive bullet will kill the mimic green enzyme.
If a mimic green enzyme reaches Blue, it will transform into a dodge orange enzyme spiking out, killing Blue and shrinking up. Another green enzyme will be spawned out of the flip door. Mimic green enzymes can also be shot in the back to kill them easier, says Doctor Nastidous. Mimic green enzymes will also shoot green enzyme faces to mimic Blue shooting a blue proton bullet.
The green enzyme faces can activate buttons- this pressure needs to be used in one level. Mimic green enzymes may not completely mimic Blue. If Blue stands in one place, mimic green enzymes will just skip mimicking being stationary. Mimic green enzymes may also skip mimicking repeated movements. It is not known if mimic green enzymes are immune to orange enzyme bullets or attacks from green enzymes.
- The first released image of Test Subject Green was of a green coloured Proto-Suit. Many fans believed this image meant that players would be able to play as a green Proto-Suit. Upon the release of the fifty-eight second trailer, it was uncertain what the green Proto-Suit meant as players would have to control Blue in its usual Proto-Suit. Upon the release of Test Subject Green, it was made known that the image was one of the three sprites of the mimic green enzyme.
- The mimic green enzyme may have been taught its movements.
- Mimic green enzymes are noticeably similar to the "transforming goo" enemies in many games, including Ditto in the Pokémon series and Liquid Phazon in Metroid Prime 3.
- The main character fighting an evil version of a character that looks like them is reminiscent of several Nintendo games which have something lie this. However, it is more like Metroid Prime 1 & 2's Dark Samus, as Dark Samus is an evil clone Samus, the main character. Both character's also have a cannon on one of their arms.
- Mimic green enzymes also behave similarly to Cosmic Clones in Super Mario Galaxy 2.