The eponymous heroine is a warrior princess who needs to defeat an invading force of anthropomorphs called the T'soas, created by a warlock named Onimen. She travels through four areas, each with several levels, as she retrieves her stolen sword and magic ring, re-forms alliances with the leaders of the elemental realms of fire, air and water, and continues on her quest to remove Onimen from her palace.
Also of note is Sia's shapeshifting abilities; in three out of four major boss battles, she transforms into a humanoid beast with claws, superhuman strength, and a mane of hair. Why? Rule of Cool, probably.
Not to be confused with Sia the musician.
Lady Sia contains examples of the following tropes:
- Action Girl: Sia herself.
- Cool Sword: It's jade. Need we say more?
- Guide Dang It!: Most of the controls are fairly intuitive, except for one boss fight in sasquatch form which requires a move that's not only useless anywhere else, but that human Sia has no equivalent for.
- Idle Animation: Sia has several, depending on the level she's in.
- Morphic Resonance: Sia is stocky and well-muscled, with a thick mane of hair, and tends to adopt a Primal Stance even when doing something disciplined like swordfighting. It makes sense after you see her transform and take all those traits Up to Eleven.
- Multiple Endings: The true ending is only unlocked after getting a perfect score on all stages, unlocking the bonus stages, and then getting a perfect score on those.
- Nintendo Hard: A short health bar, enemies everywhere, and glitches in vital places.
- No Ending: You beat the last boss, he changes into a massive demon with wings, and...he flies away. If you did not unlock the true ending, the game ends and the credits roll.
- One-Winged Angel
- Royals Who Actually Do Something: Sia appears to be a very proactive ruler even before she has to reclaim her throne by force.
- Royalty Superpower: Sia's shapeshifting is stated to be hereditary. In the Storming the Castle stages, the portraits of her predecessors are actually of their beast form.
- Sequel Hook: The man that frees Sia and becomes king of the T'soas after Onimen's defeat never has his identity revealed, while the future of the T'soas now that they have to adapt to a non-martial lifestyle is presented as something the realms take a chance on. Two sequels (or two versions of one sequel) were worked on for 2003: Sword of Sia: Lady Sia 2 for the GBA was to be quite like the original game and nearly finished, while another one for the consoles never got past the prototype stage. Both got cancelled when the studio was bought up.
- Transformation Sequence: A short one, used when Sia transitions from normal to what's usually called her 'sasquatch' form.