Hidden Test Maps

The Hidden Test Maps is a set of two small maps that are featured in Grand Theft Auto IV.

Description
As the name suggests, these two maps were created for testing purposes and are normally hidden in the game, thus cannot be reached without using Modifications. These maps are technically added along with Liberty City and the State of Alderney, but were placed way above the height limits.

These test maps are internally named as well, called "CJ_Test " and "Animviewer ":

CJ_Test
Named after CJ Dick, Rockstar Lead Prop Artist, this map contains several objects used in the game, starting from small, breakable objects, such as mailboxes, shopping carts, and wooden fences, to larger, unbreakable objects, such as wooden light posts, trees, and a FlyUS passenger plane. The ground contains large portions of different textures, both soft and hard surfaces, and small building interiors used for clothing shops (Perseus, Modo, and Russian Shop), laundromats, and the normally-inaccessible shop featured in Bull in a China Shop. Also, there is a stack of explosive barrels. Evidently, this map was purposed for the test of props within the character and the environment, and the differently-textured portions of the ground were purposed for the vehicle's handling responses when driven over these.

This map also contains the two hidden rooms used for the Venturas Poker Challenge and The Men's Room, two TV shows, as well as another room that has no collision detection, which can only be seen with the correct modification (one that can move Niko to anywhere and without falling).

One rare occasions, from 13:00 to 14:00, its possible to spot a a postman. He doesn't have voice lines and after a short time he stands still. It is unknown if he can be spotted in the city at this time.

Animviewer
This map is depicted as a flat terrain with staircases, platforms, unique concrete walls, and some objects. As the name suggests, it is intended for animation testing, like running, crouching, taking cover, and ragdoll animations when the character falls from a considerable height. At night, several colourful lights can be seen, which seemed to be purposed for light reflection.