Cooperative Testing Initiative



The Cooperative Testing Initiative, or simply co-op, is a multi-player gamemode and campaign in Portal 2 whereby two players can join up and take part in test courses built specifically for cooperative testing.

Overview
Players take the form of two robot test subjects built by GLaDOS, Atlas; the short and round blue bot, P-body; the tall and pea-shaped orange bot. Each bot comes equipped with their own Handheld Portal Device with separate portal colors. The portals are capable of maintaining the flow of things, even if it enters a partner's portal, which is essential during some test chambers.

There are five official testing courses, each with a number of test chambers within, which will test both the robots' ability to solve the different puzzles as they progress. Each chamber becomes much harder than the last, with the final test taking place outside the official Aperture testing facilities. In these tests, the bots are then put to the test, so to speak, and must use every bit of knowledge earned about the previous tests in the final one.

For the last chambers of each courses, excluding the fifth, the bots are instructed by GLaDOS to go out and locate a certain disk to be inserted into a DVD player found at the end of the course. Once found and inserted within the device, the players are given a few lines from GLaDOS before she triggers a self-destruct sequence on the duo. This is the only means of retrieving them back to the Hub.

During the testing, GLaDOS will periodically chime in and say a few choice words, either to bemoan the bots' progress or point out their tiny flaws. She even goes beyond to try and break their partnership by pointing fingers at one or the other. If either both or one of the bots' stands within range of GLaDOS' monitoring cameras and perform a gesture, it will elicit her response, depending on the gesture performed.

In this campaign, the bots will be notified that their partner has been destroyed and exactly where it did. The destroyed bot will be easily rebuilt seconds later in a chute from the Reassembly Machine. The gamemode gives an infinite amount of lives, and GLaDOS will comment on every death that occurs with dry humor or irritability. As the bots progress, they will cross checkpoints that lead into the next part of the test chamber. Checkpoints allow the bot that died to respawn at the checkpoint for shorter travel time to the next testing chamber.

Art Therapy
Set after the conclusion of the Mobility Gels course, GLaDOS has reassembled the bots for testing again and claims that it has been millions of years since they were last reassembled.

Interestingly, the sixth course was initially going to consist of advanced test chambers during Portal 2 ' s development, months before the game was released. However, this was scrapped and was removed from the final game. The Peer Review DLC to Portal 2 instead adds only challenge modes to single-player and co-op, with no sign of advanced test chambers. The Art Therapy course is referred to as an additional course instead of the "sixth course".