Animal-Themed Virtual Worlds Like Second Life

No single game fully replicates Second Life's user-generated economy and freedom with an animal focus, but these offer animal avatars and social worlds:

Animal Avatar-Centric

• Animal Jam: Kid/teen-focused, customizable animals, dens, mini-games, heavy social features.
• Star Stable Online: Horse-centric MMO; create rider + horse, explore, quests, social.
• Zoo Tycoon 2 (with mods): Management sim, but community mods add animal avatar play.

Social/VR Platforms with Animal Avatars

• VRChat: Full-body tracking, infinite user-made animal avatars, social worlds, PC/VR.
• Neos VR / Resonite: Similar to VRChat, deeper creation tools.

Life Sim with Animals

• The Sims 4: Cats & Dogs: Create/control pets, vet career, but not an MMO.
• Animal Crossing: New Horizons: Human villager + animal neighbors, heavy customization, online visits.

Emerging/Niche

• Project Zomboid (Wolf Mode): Survival as wolf pack—early access, not a social world.
• Feral / The Endless Forest (older): Artistic, non-verbal animal RP experiences.

For closest Second Life feel: VRChat with a custom animal avatar. For casual animal MMO: Animal Jam (younger) or Star Stable (horse fans).