Sphereful are large spherical enemies that are found in Keen 5.
Sphereful were probably built by the Shikadi to help guard the Omegamatic. They are indestructible and unstunnable. The main body seems to be made of a glass-like substance resistant to damage, filled with some sort of plasma-energy discharge sparking between the diamond sensor points and the interior. They are thus impressive, but surprisingly simple, doing damage by cutting anything they contact with their spikes.
They move very slowly, floating around and using the four diamond sensors on their surface to detect targets. When they find one, they move slowly but surely towards them, killing them on touch.
The official help says:
Frightful plasma orbs with orbiting diamond sensors, tread carefully by these dangerous denizens.
The name "Sphereful" is possibly a portmanteau of "spherical" and "careful" (or possibly "fearful") named after its spherical shape and dangerous nature — or perhaps just a simple -ful suffix tacked onto "sphere". Expanding on this presumed pun, its name is used in the title of one of the Keen5 background songs, "Be Very Sphereful With My Diamonds".
See also List of Keen 5 Creatures.
Appearance in Keen GBC
Sphereful appear again in Keen GBC; on the Shikadi World, where they are very different, being an earlier version of the Omegamatic ones. They are weaker than those in Keen 5 and can be destroyed. They are also not spherical, being instead only roughly rounded and mostly metal. They are no longer diamond tipped, instead being equipped with two rotating "razor sensors". They will whizz about after Keen but are much less dangerous. They are described by the game manual as follows:
Frightful plasma orbs with orbiting razor sensors, tread carefully by these dangerous denizens.