Uridium is a science fiction side-scrolling shoot 'em-up originally designed by Andrew Braybrook for the Commodore 64. It was one of the most popular games for the 8-bit home computer, and it won the award for best shooting game of the year in 1986. It was different from other side-scrolling games since the movement is permitted in 2 directions (from left to right and from right to left).
One of the main features was the parallax scrolling, in theory not supported by the Commodore 64 but achieved with a clever trick.