Fire Cannon 2 is played entirely from a 2.5D side-scrolling perspective. In terms of layout, this extra stage is a straight path with several twists and turns.
The entire extra stage is littered with flamethrowers. These flamethrowers can be mounted on the walls, floors and even ceilings, and will spit out plumes of fire in intervals. If the player touches these flames, they will take damage. A large part of the gameplay in Fire Cannon 2 is about the player timing their movements in accordance to the flamethrowers so Sonic/Shadow does not get killed before reaching the goal.
Upon beginning Fire Cannon 2, stomp through the breakable Containers in the floor and let Sonic/Shadow drop to the ground. Once on solid ground, proceed to the right while dodging flamethrowers until a Spring shows up. Use that Spring and follow the flamethrower-ridden path it takes Sonic/Shadow to. After passing through an underground loop with flamethrowers, the player needs to smash through some Containers blocking the player's path through a wall.
On the other side of the wall, climb a wide vertical shaft with flamethrowers. At the top of the shaft, take the path on the left, which has a Spring hidden underneath some breakable Containers. Use that Spring to get to a higher area, and climb then the flamethrower-ridden shaft on the left in the aforementioned area. At the top of that shaft is a Spring on the left. Use that Spring to get to a higher area, which has a shaft on the left. Stomp through the Containers blocking this shaft and follow the flamethrower-mounted path downward until a Dash Panel launches Sonic/Shadow back the way he came. The player will soon after hit a Dash Ring that will take them to the goal.