An action game set at a time when nascent, insectoid life forms battled each
other for survival and for domination of the ecosystem, in an ancient epoch at
the dawn of life on Earth (or thereabouts). The player, cast in the role of a
scorpion, is tasked with overcoming an incursion by a particularly mean strain
of killer spiders.

Similar to Tempest, the player patrols the top edge of a tunnel seen from a
bird’s-eye view, as enemies rise up from the depths. Firing volleys of venom
will destroy the unwelcome arachnids as they try to scale the walls; if they
manage to crawl their way to the top, they open holes in the tunnel wall
(which spell death for the player). Each wave of attack adds an intermediate
platform within the tunnel, which the spiders can move along, change
directions and dodge the player’s fire.

Also traveling along the top edge is a special color-changing brick: one color
means instant death for the player; the other can be picked up, which
increases the score multiplier, acts as a shield and allows the player to fix
broken sections of the tunnel wall. Good aim is encouraged – extra lives may
be gained by keeping a high percentage of hits.