Franchise: Ghosts 'n Goblins

When Elite Software obtained the license to make a video game based on the ThunderCats cartoon, they were unsure if they would be able to complete the game in time for Christmas, and as such outsourced a second ThunderCats game to Paradise Software. Neither game could be finished before the deadline, and as such Elite instead attained the rights to a near-finished game titled Samurai Dawn by FTL Games and released it as ThunderCats: The Lost Eye of Thundera.

Elite's in-house ThunderCats game got pitched to Capcom as a sequel to Ghosts 'n Goblins, but was not picked up due to Ghouls 'n Ghosts being in development at the time. It would be released as an original IP, simply titled Beyond the Ice Palace, featuring a character who in certain versions of the game resembles Lion-O.

Paradise Software's ThunderCats game remains shrouded in mystery, but it seems incredibly likely that the game was released as Bomb Jack II, owing to the C64 version of the game including a rendition of the ThunderCats theme song (stolen music being somewhat of a tradition for the Bomb Jack franchise), not featuring any bombs, and having a protagonist that more closely resembles Lion-O than Bomb Jack.

The Japanese NES version of Ghosts 'N' Goblins didn't feature any continues, forcing the player back to start of both cycles when they got a game over. By contrast, the international NES version, featuring unlimited continues that sent you back to the last checkpoint, is still considered extremely difficult.