Fire Emblem: Archanea Saga is a standalone game released in 4 parts, made in the same engine as Fire Emblem: Mystery of the Emblem, that take place between the prologue and the first chapter of Fire Emblem: Shadow Dragon.
The game was only released in Japan and was distributed with the Stellaview peripheral of the Super Famicom.
Each part of the game used one map with a time limit, the goal of the game was to collect as many points as possible before the time ran out without your Lord unit being defeated. Most of the games dialogue was voice acted and had some original characters along with characters from the Fire Emblem games Mystery of the Emblem, Shadow Dragon, and The Blade of Light.
The game was later included with the remake of Mystery of the Emblem as an extra mode, without the timers or the voice acting, for the Nintendo DS called Fire Emblem: New Mystery of the Emblem. This was also only released in Japan.