Panels are square shaped interactive objects in Flue. The outermost edge of a panel appears to be slanted towards the centre of the screen. Panels are encountered in all levels of the game. The green slime can move onto all panels except for red ones.
Red panels are the only hazardous panels in Flue. They appear dark red and are separated by light red red lines. Red panels cannot be regularly moved on to, and are in most cases not hazardous because of this.
The only way to move on to a red panel is to be propelled on to one by a pink panel. When this is done, the green slime will impact the red panel and die. Red panels primarily make up the wall and background of the level, and are in most cases not meant to be interacted with.
Finish panels are found only at the end of a level, and upon either coloured tile being moved on to by the green slime, it will be propelled into an opened hole in the screen, and into the next area (proceeding to the next level). Two rows of grey and tan panels are encountered at the end of the level, despite the player only able to reach the first row.
Orange panels are the most abundant of all panels and make up the majority of each level. They can be moved on to by the slime, and serve no other purpose, other than being arranged in such a way that, often in conjunction with other panels, allow the green slime to reach the end of the level.
Pink panels propel the green slime upwards when the panel is walked on to by the green slime. They can move the green slime to isolated or otherwise unreachable orange panels, though sometimes they are used to get around spiked slimes or red slimes that would be appear otherwise impossible to pass.
Despite being used for level progression, a few panels in the game are placed so that they deliberately kill the player, as these panels will propel the player on to red panels that are opposite the pink panel. Pink panels appear less frequently throughout Flue.