Metroid 1.5 was an undeveloped new game in the Metroid Prime series, internally pitched at Retro Studios between the development of Metroid Prime and Metroid Prime 2: Echoes. This lost project was found in 2011 thanks to online research by Mama Robotnik on the NeoGAF forum, who unveiled the Metroid 1.5 design document written by former Metroid Prime designer:
“This adventure would take place immediately after Samus takes off from the surface of Talon IV. Upon exiting the planets surface, Samus decides to take a long rest in her Cryo chamber as her ship autopilots home. However, something goes wrong and Samus’s ship computer hones in on a distress signal. The distress signal is coming from a huge alien vessel (huge, like the size of several Star Destroyers) that is drifting out in space. As Samus’s ship approaches the alien craft, a tractor beam activates and the Ship is pulled into one of the gigantic docking bays. As the ships doors close, the gigantic vessel folds and enters a parallel dimension, thus begins Samus’ new adventure
Upon awakening, the ship appears to be abandoned, there is no power except for auxiliary lights and telemetry from computers. It is up to Samus to unravel this mystery. The mystery being that the ships AI has gone mad and the ship is actually a war vessel that is on a collision course with a peaceful planet. Its goal? The entire enslavement of the race of beings on said planet as well as natural resource stripping as its (the planets) destruction. So in essence, the ship AI has split into several different personalities, and is playing a deadly game with Samus. The Alien inhabitants of the ship are also in a state of suspended animation because as the ship travels through the parallel dimension, the alien inhabitants are being created and refined for warfare until the ship arrives at its destination and assaults the planet . However, the robotic and automated entities are not, these will be the primary enemies that Samus must deal with. In addition, Samus must also deal with the ships cunning AI, who will all the while be taunting her and trying to trick her at every opportunity.”
“The Main reason Samus and possibly other Bounty Hunters are being pulled into this ship is to assimilate their best and most deadly abilities into the personality construct of not only the ships AI, but also into the actual Alien Inhabitants in order to further their quest for perfection. As the ship reaches its target, it will unfold into this dimension and begin its attack. This has what the ship and Alien race who created it has have been doing for past thousand or so years, going from planet to planet, assimilating the most violent parts of a culture and asserting it into its own being.
The main goal for Samus is to disable the engines of the ship, destroy the AI, and eradicate all life forms on the ship. The catch is that even though Samus is all powerful from her previous item acquisition on Talon IV, she will be limited to use them in certain areas of the ship due to the containment matrix that the Rogue AI has set up all over the ship. This will force the player to handle situations differently than expected, and once the containment matrix is disabled, Samus will be free to use all of her abilities. Due to being in a parallel dimension, there are areas within the ship where floors may become ceiling due to gravity being reversed, Time may run backwards, (illustrated by creatures and machines moving in reverse, water moving up into a faucet) and other sorts of environmental weirdness, that Samus as well as other Bounty hunters will have to learn to adjust to in order to survive.”
“Mad AI, the central computer of the ship has gone crazy, it sees inviting Samus onto the ship as a game for its amusement. Will taunt and try to trip Samus up at every move. The Mad AI has four distinct personalities : The Child, The Killer, the Martyr, and the Fool each one is deadly and utilizes different tactics and techniques.”
This cancelled project was meant to have a short development time, to release it shortly after the first Metroid Prime while the main team would take their time to develop the true sequel:
“So this is pretty much what I think we could crank out in a year, A Smaller Adventure with expanded mechanics and a few new ones thrown in. The beauty of spaceship design is that a lot of corridors and hub rooms can be reused over and over again, with minor variation; it also lends itself well to our room/door/hall layout. Plus, we can make the world denser by exploiting the super structure of the ship using morphball mechanics. Even though the idea of an AI gone mad has been used before in games as well as films, I feel that we could put a unique twist on it. And by allowing Samus to use only certain abilities in certain parts of the game, we can get a fair amount of replay value by offering the player different solutions to a single problem. This I feel would satisfy gamers who completed Prime and are hungry for something more with a few new mechanics and ideas thrown in.
With the addition of the co-op multiplayer components I have noted in the previous paragraphs, I feel that we would still have a game that feels like Metroid, albeit the feeling of Isolation would no longer be there, at the expense of the multi-player experience. However, I think the by unlocking the additional multi-player modes, after the actual game is completed, it won’t detract from the experience. Unlike TimeSplitters 1 and 2, we can keep the player focused on the main portion or adventure of the game which is what Metroid is all about.”