Plasma Cannon 1 takes place in a specialized area within the interior section of Network Terminal.
Plasma Cannon 1 is played entirely from a 2.5D side-scrolling perspective. In terms of layout, this secret stage is a straight path with several twists and turns. The details of the level layout may vary however.
The only obstacles encountered in Plasma Cannon 1 are the titular plasma cannons. These obstacles take the form of floating, gray balls with green holes in them. In gameplay, they spin around periodically, scattering green energy balls as they turn. Touching these energy balls will damage the playable character. However, the energy balls will disappear after hitting any surface, meaning the player can hide behind platforms and walls to dodge them.
At the beginning of the secret stage, run past the plasma cannon above the road and proceed to the lower path ahead. As the player then makes their way up the ascending path they arrive at, they have to watch out for another two plasma cannons. After the second of these plasma cannons, the player has to follow the path downward and then to the right. Just ahead however, is another plasma cannon that the player to pass.
Once on the other side of the plasma cannon, use the local Spring to enter a tall shaft. While climbing this shaft, the player has to watch out for another plasma cannon. Once at the top of the shaft, the player has to get past two side-by-side plasma cannons to reach the room on the left where the goal is.