An MSX game released in 1987 by Konami. The sequel to Knightmare. This is one of the games I remember having played for countless hours when I was little. Very addictive.
The Maze of Galious is a platform game with slight adventure and RPG elements. It takes place in a castle called Castle Greek and ten Worlds, the doors to which are found in various locations in the castle. The doors are all locked and can be opened with the correct Great Key. The key to World 1 can be found in the castle, and the keys to later worlds can be retrieved by killing a Great Demon that resides in the previous World. The objective is to search the castle for items - some useful, some essential - and the doors, and to reclaim all the Worlds from the Great Demons.
The player controls two characters, Popolon and Aphrodite. They both have their own strengths and weaknesses - Popolon can destroy rocks faster than Aphrodite and pass through revolving doors and the height of his jumps can be controlled, while Aphrodite can survive long periods under water, fire arrows faster (limited to three arrows simultaneously on screen while Popolon is limited to only two) and have more mines simultaneously on screen (again limited to three while Popolon is limited to two). Most of the weaknesses can be defeated with certain items. You can freely switch between the characters unless either of them is dead, in which case you need to resurrect the dead character at a certain point found in the castle. Two dead characters means Game Over, of course.
Both characters start with a very low maximum vitality (hit point count). Discovering a Great Key will increase the maximum vitality of the character who picks it up. Vitality can be restored to maximum by two ways - filling the experience gauge which can be found under the vitality gauge by killing monsters, or materializing a fairy which can be done at certain places in the castle and touching it. The vitality and experience system brings a simple tactical element to the game - alternating between characters when picking up Great Keys, using a character with low vitality but high experience while in a room with easy monsters, etc.
A NES version also exists. It contains some major differences from the MSX version. For instance, there are no rocks or item icons, and areas of the castle cannot be entered in the beginning, making the gameplay more linear than in the MSX version.