The game takes place after Portal 2 and the player is guided by a personality core Nigel to complete puzzles in the Aperture Science Enrichment Center.

[3] The game also features a modified level editor, allowing users to create their own maps, which can be utilized in the single-player or cooperative modes.

After waking up in a stasis chamber, the test subject is introduced to basic controls of the game as well as a personality core Nigel, who was designed by GLaDOS.

In the alternate ending, which is unlocked by closing the fire pit with a button, Nigel, as ordered by GLaDOS, allows the test subject to return to surface, which is later revealed to be a simulation.

After attending a Valve-hosted closed beta for the 2012 Perpetual Testing Initiative update, Roman asked Valve employees if they had planned on adding a paint gun to Portal 2.

[5] Prior to creating Aperture Tag, Roman also designed maps in the Source engine editor.

After visiting Valve offices again in May 2013, Roman decided to make Aperture Tag a full modification release instead of a map pack.

Benjamin Thomas Blodgett helped program the compilation of maps in the modified in-game level editor.

[5] The Aperture Tag Team submitted the map pack for Steam Greenlight in January 2014, in order to publish the game as a standalone mod.

[10][4] The game features a custom soundtrack composed by Harry "Harry101UK" Callaghan and Christopher McEvoy, as well as the song All These Walls by Abarax.

Christopher Livingston of PC Gamer praised the concept and mechanics of the paint gun and its auto-save system, but ultimately said that the game's "price is a tad optimistic for what you get".

[3] Both Livingston and Aleksandr Levahin of VK Play noted many community chambers were available for Portal 2 at no cost, as opposed to the paid nature of Tag.

[1][8][9] Journalist Steven Brasley, on the other hand, praised the design, scenery, and progressive increase of difficulty in puzzles, which he thought resembled the Portal series.

[9] Levahin described the puzzles as occasionally challenging, but criticized their textures, stating that the game looked worse than Portal 2.

[3] Livingston said that his "jokes certainly aren't funny", that he had trouble deciding what his personality is, and that the quality of voice acting and writing was not on the level of Portal 2.