A compelling feature for a game or story with a title like would be a "Corruption & Extraction" Meta-Minigame.

Since the title references a compressed file ( .rar ), the core mechanic could revolve around the monster girls from a rival’s digital or magical vault. Feature: The "Data Siphon" Heist

Instead of just winning a battle, you have to strategically "extract" the harem members during high-stakes infiltration missions.

You use a specialized tool (the "Unarchiver") to bypass their current "encryption" (loyalty to the original owner). The Gameplay:

It leans into the "Stealing" aspect of your title while playing with the file-extension theme. It turns the harem members from static prizes into active participants in a heist.

Infiltrate the rival's lair to find where the harem members are "stored."