Ephemeral Fantasia features traditional role-playing video game turn-based battles, with a variety of playable characters and skills. Additionally, there is a guitar minigame that can be played several times throughout the course of the story.
The recruitable characters in the game are as follows:-
Mouse - The main character of the game who uses a sword to attack, and his trusty guitar Pattimo, a 300-year-old talking guitar that is part of the Romel Clan. Mouse never is given any dialogue. He is also a "Soldier" rank in the ancient KANON clan, a clan that has time control abilities.
Kyte - A rotund sailor with a taste for his drink, the 'Shark Killer'. Later, he tells Mouse of his ship, the "Matilda," which was sunk by immensely powerful monsters when he and his crew tried to sail away from Pandule. He is the sole survivor of the crew, and endeavors to exact his revenge on the monsters. He uses dried, hardened fish to attack enemies.
Claire - A heavy drinker, Claire is the watchmaker of the game and is the key to saving your items and money each weekly cycle with her Time Vault. Uses a chain for a weapon. Until later in the game, she is not aware of her rank in the KANON clan as that of a "Master."
Rummy - She is a castle guard and Mouse's guide. She loves Mouse and is deeply jealous of the princess, Loreille, since Rummy believes her to be more attractive than she is. A keen fist fighter and martial artist.
Bagoth - The leader of the castle guard and commander of the island's soldiers. He is loyal to a fault, and uses a mace to beat opponents.
Plosi - A painter widely known to be an old pervert, he has no lust for battle and rather weak skills to match, although his magic abilities are quite decent. He is enlisted to paint Loreille's portrait for the wedding. Uses a paintbrush to attack.
Ano - The magic scientist of the castle, his title being a slight contraction in terms. He has powerful magic, using his book to analyze and attack foes.
Rinna and RindRinna - A stubborn little girl who takes a fancy to Mouse initially, but then to Beak when she meets him. She has two forms; the first uses a broom to attack, the second uses dancing and a tambourine.
Gallhint - A bandit who is key to progressing the game's story due to the bandit's raid on the castle. Uses daggers to rip his enemies apart. He cares deeply for his friends and his girlfriend, and is willing to die hundreds of times to save them. He is also a "Soldier" rank in the KANON clan.
Beak - Part of the Golden Three—Mouse, Beak and Fang. A very strong ally who wields a very big sword.
Lloyd and Lloyd-L - Lloyd is the robotic enigma created by magic science, and it is recovered during the allies' infiltration of the castle. His second form is that of Loreille. Claire later repairs him, making him a playable ally.
Fang - Part of the Golden Three—Mouse, Beak and Fang. Fang plays the flute and wields a large trident.
Grantus - Part of the KANON, Grantus is, like Mouse and Gallhint, a "Soldier" rank. An ally Mouse actually kills in a duel, yet resurrects by putting a wish flower on his grave. An incredibly strong ally who charges foes with his axe.
There are also non-playable characters (NPCs) that are important to the storyline as well.
Pattimo - A 300-year old living guitar that is a member of the Romel Clan. The two have been longtime partners, according to him, and Mouse also uses him as a sheathe for his sword as well as a fully functional lute. He plays the role of the comic relief character and is shown to be quite sarcastic. Oddly enough, he does most of the talking and scheming.
Xelpherpolis - The main antagonist of the game. He uses time magic to make the island of Pandule repeat the same five days indefinitely, drawing on the powers of the spirits on the island and ostensibly on his own, since he is a "Master" rank in the KANON clan.
Loreille - The princess of the island of Pandule that Xelpherpolis is arranged to marry in five days. She is also the single most powerful member of the KANON clan--"Holy" rank—although this is only revealed later in the game. Before Xelpherpolis came to the island to ask her hand in marriage, she was unaware of her rank in KANON, and was thus easily manipulated by him.
Jawarro - One of Xelpherpolis's evil minions who is erudite in the field of magic science. She created Lloyd and helps Xelpherpolis control the island's inhabitants' hearts. When Mouse defeats her, she discovers that she is closely related to Claire. Like Xelpherpolis and Claire, she is a "Master" rank in the KANON clan.
Twinboom - The third of Xelpherpolis's evil minions who governs the time loop week after week. He controls the time loop, and when Mouse defeats him, the time loop ceases. He professes to be "far superior" to humans. Like Xelpherpolis, Claire, and Jawarro, he is a "Master" rank in the KANON clan.
Old Hag - Her true name is unknown, and she prefers to be called "the Old Hag." Her main role in the storyline is to give Mouse the Spirit Encyclopedia in order to help him to defeat Xelpherpolis.
Jailson - He is Professor Ano's mentor and superior. He is supposedly the one person on Pandule whose knowledge of magic science is superior to that of Ano.
Zenne - Gallhint's girlfriend and a tough fighter and bandit. She and Gallhint mean the world to each other.
Ephemeral Fantasia is similar to The Legend of Zelda: Majora's Mask in that the story transpires over a constantly looping period of five days. This is caused by a time loop created by the main antagonist, Xelpherpolis. In order for the time loop to be halted, Mouse must travel through the same five days multiple times.
This game follows Mouse, who has been summoned by a powerful figure on a remote island to compose a song. Xelpherpolis invites Mouse to play at his wedding, no doubt because of his fame as an excellent musician. Of course, Xelpherpolis doesn't expect him to solve the mystery of the island and free its inhabitants.
Ephemeral Fantasia was originally to be released on the Sega Dreamcast. An interview with development team member Makoto "M2" Moribe in Famitsu reveals that additional content planned for the Dreamcast version was cut when the game was moved to PS2. The Dreamcast version of Ephemeral Fantasia was to feature cameos by Sega characters including Sonic the Hedgehog, Ulala, Ryo Hazuki, and, oddly enough, notable Sega developers Yu Suzuki and Yuji Naka.
The game had received mixed to negative reviews from game critics. Edge scored the game 6 out of 10.