Superb shaded graphics, impeccable animation, fast and smooth scrolling (not a common combination on the Speccy) and of course that completely addictive gameplay all go to make Uridium possibly the greatest Commodore to Spectrum conversion of all time - no kidding.
You cruise along in space as the impressive battleship rolls under you, its defence systems are activated, alert sirens sound. Intricate waves of aliens streak forwards (mechanical doughnuts, starfights and lemons) intending to mount your head over their mantelpieces. You fight - a fiery altercation in space - spinning and weaving, flipping over to avoid their fire, dodging the walls and pillars that read up all round, raining your lasers on the surface of the ship. You win the next fight, land and warp to the next mechanical behemoth - wondering about the fifteen more to be destroyed after that.
The graphics are fluid and fast, and grappling with inertia is a difficult and skillful affair. The scrolling is impeccable and alien attack waves tough and faster than a speeding bullet or cliches to that effect. In fact though Uridium was released in October of '86 it still looks pretty good today.
If you are extremely prejudiced towards aliens, want to fry their butts off, and would like to pilot a ship at incredible speeds then Uridium's the game for you.