Game takes place in the remote future. Players wake up in a research facility with no memory to find that they have been experimented on, specifically with their arms. The characters have a device attached to their arm (right arms for player one and left arm for player two). Attached to their arms are identical devices. These devices create an elastic energy beam. This beam can be turned off and on by the users and it is restricted to a certain length. Other features of the device include a contract and retract function. The players can use this beam to attach to certain surfaces as well as to each other. By using these devices the players can effectively maneuver through previously impossible terrain. Using this to their advantage, the players escape a condemned research facility and navigate through a ruined city. It is not safe to be on the ground of the ruined city due the ground being coved with toxic chemicals, which is left by years of warfare. In the city, players must navigate above the ground to escape in search for answers.
There is a difference between the players. Player One is a male and is stronger than his counter part who is female. However, she can squeeze into small spaces. Players can shoot their beam to attach it to a compatible surface or the player can shoot their beam at their teammate, who can catch it with their device. Once attached the beam can be contracted or retracted. Furthermore once the beam is attached, it can be stretched with the right amount of force. This can come in handy if players need to catapult themselves to a previously unreachable location. Thus it can also be clear that the beam is strong enough to hold the weight of each player. A player dies if they fall from a significant height, fall into a never-ending abyss, or if they land in the toxic chemicals. Moreover, a player does not have a health bar, ammo or map. Thus there is no HUD because there is nothing to display.
Using the help of one another, physics and the functions of their newly obtained bionic arms, players can successfully navigate through hopeless terrain. There also happen to be different paths in which players can take. Some of which are more daring and some safer, but all paths lead to the end. The riskier paths tend to be shorter where the safer paths tend to be longer and more complicated. Because of the size and strength difference, there certain areas require the specific player to use their unique attribute so that the pair and proceed past the obstacle.
The game is centered on checkpoints and save points. There are lives involved. If one of the two players dies, both must restart at a pervious checkpoint. Saves are not save states. Players can only save at checkpoints.
Bionic Commando is similar in the way that the player can navigate through terrain which is directly related the inclusion of a bionic arm that attach on to surfaces as well as contract and retract. The difference between the games is the game play and functionality of the bionic arm. The bionic arms in Fused can only attached to very specific surfaces as well as other bionic arms. Furthermore, Fused relies highly upon co-operative play where Bionic Commando is a single player game. Furthermore in Bionic Commando, the player uses weapons to fight enemies, where Fused doesn't have enemies to fight.
Portal is similar game type. Like Portal in Fused, there is not much known about the background of the time or the characters. Also similar to Portal, the characters in Fused are apart of a research project. These characters then escape their confinement at the facility. The difference between Portal and Fused is the game play continuation of the story. The main objective in Portal is to escape the research compound where in Fused the characters are continue past the research facility through a desolate city in search of answers. Although both games are puzzle games, the differences between the two come out when players attempt to navigate through these puzzles. Where Portal is single player, Fused relies heavily upon co-operative play. Not to mention that the difference between the devices used in each game are not similar in any means.