In the game of CONS you are a sentient warrior cons cell. In each randomly generated mission you will infiltrate and sabotage an alien military installation.
The player is composed of several square 16x16 pixel pieces whose movements follow one another like a centipede. At the start of the game, there is the "agent", i.e. the head of the snake, and three segments. Each body segment is one inventory slot; adding body segments upgrades one's inventory, but since segments are also susceptible to enemy fire, these upgrades also increase your vulnerability.
Each enemy base is rectangular in shape, where each grid square (or "sector") therein represents a different type of facility (and a different randomly-generated game level.) This is the game's "overworld map" if you will, but it is limited in size to between 4x4 and possibly as high as 16x16 on a higher difficulty setting.
In each sector, one or more goals must be completed, such as defeating all enemies, defeating a particular enemy, retrieving an item, or unlocking a doorway. Once your total mission is complete, a victory/scoring screen is displayed, and then the game ends. Death also ends the game.
The contents and varying goals of each sector must be discovered as the player visits them; only squares adjacent to a sector whose objectives are completed, may be identified and visited. One may complete goals and sectors in any available order, and return to different areas as needed (for example, running back to an Archive to retrieve more healing items.)
Each sector generator has a "level" parameter that can trigger additional behaviors intended to make a level more difficult and more rewarding. The general difficulty of the game can be ramped by generating map squares of appropriate difficulty levels.