Depending on your specific area of interest, this query might relate to: ESS RCPLUS Sound Editor There is a sound editor software for ESS products (often used in RC modeling) called Version Context

Based on available information, "RCPLUS" typically refers to the configuration software for the of RC engine sound simulators (such as the Go to product viewer dialog for this item. Go to product viewer dialog for this item.

: It allows users to personalize sounds for their models. A "v18 repack" could be a much later, unofficial, or incorrectly labeled community-distributed version. Software/Game Piracy ("The Scene")

Yes, most repacks are designed for offline use. In fact, you should keep the machine offline to prevent activation checks.