Redesigned Dalek

Daleks in heavily redesigned casings existed on Skaro in 2254.

History
In 2254, when the Seventh Doctor was sent to Skaro by the Time Lords to get back a sacred Time Ring stolen by Davros, he encountered a number of Daleks in unique tank-like casings that had no eyestalk, but instead two round eye-holes in their top section. They were also devoid of sense globes on their base sections and had modified weapons.

These Daleks appeared to act as guardians throughout the Dalek capital, with some spotted patrolling outside by the Doctor while two others stood at the Dalek Emperor to protect their supreme leader. The last two Daleks were destroyed alongside the Emperor in an explosion the Doctor caused with his sonic screwdriver. (GAME: Dalek Attack)

Behind the scenes
These Daleks were originally created by Raymond Cusick (who had designed the original Dalek casings for The Daleks in 1963) for the Doctor Who Magazine Tenth Anniversary Special in 1989.

The in-universe context presented for the schematics was that Cusicks' drawings were blueprints for a new and stronger race of Daleks, supposedly coming directly from the hand of Davros. Dalek Attack (the only story to date to include this Dalek variant) does not specify this as their origin, but shows the redesigned Daleks as existing on Skaro at a time when Davros is welcomed there by the Dalek Emperor, which is consistent with this offscreen backstory. On the other hand, the redesigned Daleks as they appear in Dalek Attack discarded some details of Cusick's original pitch; most notably, they were intended to be of a dark green or dark blue colour to suggest they were made out of "unusual metals", whereas in the video game they are simply a dull gray.