Here are Australian-available companies (brands) that produce complete, balanced diets specifically formulated or marketed for indoor adult cats — with a representative product page for each:

• Royal Canin — Indoor (balanced dry diet for adult indoor cats). (justforpets.com.au)
• Hill’s Science Diet — Adult Indoor (balanced dry diet formulated for indoor cats). (petpost.com.au)
• Purina (Pro Plan / PURINA ONE) — Indoor / Indoor Hairball formulas (complete diets for indoor cats). (purina.com.au)
• Advance (Australian-made Advance brand) — Adult Indoor formulas (balanced diets tailored to indoor cats). (petbuy.com.au)
• Black Hawk (Aust. brand) — “Indoor / Healthy Benefits” indoor cat dry & wet formulas (complete & balanced). (blackhawkpetcare.com.au)
• Ivory Coat (Australian brand) — Indoor & Hairball and other complete cat diets (balanced nutrition; Australian-made). (ivorycoat.com.au)

Notes:

• “Indoor” formulas are typically balanced for maintenance and include ingredients to help with hairballs, stool odour and controlled calories for less-active cats; check the product label (AAFCO/FSANZ or manufacturer statements) to confirm “complete & balanced” for your cat’s life stage.
• If your cat has medical issues (urinary disease, weight concerns, allergies), consult your veterinarian before switching foods.

If you’d like, I can: (a) expand this list to include smaller/specialist Australian makers or NZ imports sold in Australia, (b) show nearby retailers that stock specific products, or (c compare ingredients/calorie levels between two of these indoor formulas. Which would you prefer?