However, the publisher was afraid that such a gigantic universe would cause disbelief in players, and eight of these galaxies were chosen for the final version.[4] Other notable early examples include the 1985 game Rescue on Fractalus that used fractals to procedurally create, in real time, the craggy mountains of an alien planet and River Raid, the 1982 Activision game that used a pseudorandom number sequence generated by a linear feedback shift register in order to generate a scrolling maze of obstacles.