City gates

City gates is an easter egg map which is only accessible through the metro station at Turnip Hill. The gates are the entrance to the underground city, which is a popular myth in Stalburg and is probably the hideout for Stalburg Underground.

Gameplay

It starts in a collapsed tunnel with a minitrain. Mark has to find his way through some doors leading to Open Sewer and then take an elevator down to a large cavern with some doors on one end (this area is pictured in Elo's hideout). These doors can be unlocked with the code 4027, which gives the player the "Error" Achievement. Any other code will give the player the "Underground Justice" Achievement, in which Mark is interrogated by a person in a diving suit and is later killed, which will end the game of INFRA.