Krull is a science fiction film not set within the Solar System which was released in 1983 and is directed by Stanford Sherman.
Rumoured to be the official Dungeons and Dragons film but just before the film came out in the cinemas, the franchise holders changed their minds. The film became just another sci-fi/fantasy. It is set on the planet of Krull which tells the story of alien invaders and a king determind to defeat them.
An alien race (known as the Slayers) led by a monster called the Beast lands on the planet Krull with the objective of conquering the planet. Two great kingdoms put their hatred behind them as one of their sons and one of their daughters marry thus uniting the kingdoms. During the wedding, the Slayers attack and kill the Kings whilst taking away the bride. The Prince whose destiny it is to be King leads out a small force to bring back his wife. Before he can rescue his wife, Ynyr tells him that he must first obtain the Glave, a throwing weapon that is the only thing that can kill the beast. He encounters a group of escaped thieves who become his army and a soothsayer who will lead them to the fortress. For the comic factor, there is Ergo who repeatedly turns himself into animals instead of his target. The fortress does not stay in one place but moves all over the planet. After the soothsayer is killed, they turn to the Widow of the Web to guide them to where the fortress will next appear. Like in all good films, they break into the fortress, rescue the bride and kill the monster. The fortress crumbles after the Beast has been killed.
For an alien race that can travel between planets and use laser guns, their form of transport is quite unadvanced in that they are horses.