The world's flora and fauna emit unique musical signatures, combinations of which cause dynamic shifts in audio based on the player's surroundings.

Key first conceived Proteus as an open-ended role-playing game akin to The Elder Scrolls IV: Oblivion but, because of the work required for such a project, later redesigned it to be "nontraditional and nonviolent".

The island is drawn in a pixel art style and consists of hills, trees, structures, and animals such as frogs and rabbits; the layout of these elements is different each time the game is played.

This idea was ultimately cut because Key and Kanaga felt it would detract from the game's exploratory emphasis and instead turn it into a creative tool.

[19] Key apologised when the Artifact Edition had not yet shipped at the end of its release year, and offered to refund customers upon request.

[48] An IGN preview found the game to be "delightfully intoxicating", unique, and intriguing, with the author replaying it multiple times.

[49] PC Gamer likewise responded positively, drawing particular attention to the game's changing soundtrack and the ways in which it coherently reacts to the player's movement.

[28] A Shacknews staff poll named the PC version the seventh-best game of 2013, calling it "delightfully devoid of explanation".

IGN's reviewer commented positively on the replayability, finding that the game provided a deeper experience on each subsequent playthrough.

[6] GameSpot was less positive, writing that while some events and locations were not guaranteed on each generated island, later portions of the game were less interesting due to their familiarity.

[4] Likewise, PC Gamer said that towards the end of the game they began to find it aimless and unstimulating, in particular because of the sparsity of animal life.

[29][30] Pocket Gamer gave a positive review, praising the audio and the extra features present in the Vita version such as PlayStation Trophies, which provided a reason to replay the game.

[36] Many players and journalists debated Proteus' status as a video game, citing aspects such as the lack of goals or objectives.

[6] Edge's reviewer contended that the day/night cycle, changeable weather, and a player-triggered change of seasons qualified Proteus as a legitimate game.

[34] Key responded by pointing out that, while the product does include rudimentary game mechanics, interacting with them is optional and they do not usually provide feedback.