Waterslug

The Waterslug is a creature in Subnautica 2, one of the first alien fauna species confirmed for the game. It was revealed through a creative alternate reality game (ARG) that used an in-game Time Capsule mechanic from a prior franchise title to deliver hidden clues to players.

The Time Capsule ARG

Starting in July 2024, developers at Unknown Worlds began planting specially crafted Time Capsules began planting specially crafted Time Capsules into the in-game messaging system of a prior franchise title. Time Capsules are an endgame feature where players leave messages, screenshots, and items for other players to discover in their own playthroughs. The developer-planted capsules were designed to look like normal player entries but contained images of a creature that did not exist in any prior franchise game.

Identifying the capsules

Community members identified the capsules as developer-planted through several distinguishing features:

• Each capsule carried the hashtag #PEEPERSRULE in its database description

• The screenshots showed close-up images of a creature not present in any prior franchise game

• Each capsule name followed the format "TC" followed by a string of numbers

• The images were macro-photography-style close-ups showing only fragments of the creature's body, deliberately cropped so no full-body view was visible

By July 29, 2024, gaming outlets had covered the story, and three Time Capsules had been discovered containing Waterslug images.

The hexadecimal puzzle

A Reddit user identified as _Erod_ made the key breakthrough. The numerical strings appended to the "TC" prefix in each capsule's name were not random: when converted from hexadecimal to ASCII text, they spelled out the word WATERSLUG. This hexadecimal encoding served as both the creature's name reveal and a puzzle for the community to solve collaboratively.

Developer Scott MacDonald (forum username "Obraxis") acknowledged the capsules on the Steam forums with deliberately coy responses, replying to a screenshot post with a shrug emoji and telling Discord users "Huh. Funny that." when fans shared the images. He subsequently confirmed the name "Waterslug" directly after the community decoded the hexadecimal message. Reddit moderators cryptically stated that "there may or may not be others to find," suggesting additional capsules were still hidden.

Physical appearance

The three Time Capsule images each showed close-up shots of different anatomical sections of the Waterslug, intentionally cropped to prevent a full-body reconstruction. The screenshots revealed:

Reddit user _Erod_ built a fan 3D model of the Waterslug based on the three partial screenshots, attempting to reconstruct the full creature from the fragments. The model was shared on the official forums as a speculative interpretation.

Post-ARG appearances

On January 24, 2025, Unknown Worlds posted a birthday celebration screenshot that featured a Waterslug, marking the first time the creature appeared in an official developer image outside of the hidden Time Capsule context. This confirmed the Waterslug's continued presence in the game's development and provided a clearer look at the creature than the cropped ARG images had allowed.

Behavioral hints

The in-capsule caption text provides the only behavioral hint about the Waterslug. The message "I think it's friendly?" (written as in-universe flavor text by the developers as part of the ARG) suggests the Waterslug may be a passive or non-aggressive creature. However, this is flavor text rather than a direct developer statement about game mechanics, so the creature's actual aggression level, threat classification, and defensive abilities remain unconfirmed.

Significance of the ARG

The Waterslug ARG was notable for several reasons. It arrived before Subnautica 2's official announcement, making it one of the earliest concrete confirmations that a sequel was in development. It demonstrated Unknown Worlds' willingness to use their existing games as a marketing platform. And it repurposed an in-game asynchronous-connection feature (Time Capsules) for an entirely new purpose.

The ARG also showed the community's collaborative puzzle-solving ability. The hexadecimal encoding, the #PEEPERSRULE hashtag, and the developer's deliberate non-answers created a layered mystery that required collective effort from Reddit, Steam forums, and Discord to unravel.

What remains unknown

As of March 2026, the following details about the Waterslug have not been officially disclosed:

• Full body shape and complete visual profile beyond the cropped close-ups

• Exact size and size class (small ambient fauna vs. larger creature)

• Specific biome habitat on Planet Zezura

• Whether it provides specific DNA adaptations when sampled with the Biosampler

• Confirmed behavioral patterns (passive, defensive, or neutral)

• Bioluminescent properties (if any)

• Diet and ecological role in Zezura's food chain