This feature would act as a pre-check script or built-in function in a launcher to handle the common headaches associated with multi-part game archives.
To make this "feature" useful, you should focus on an to ensure the download is valid before you waste time trying to install it. Proposed Feature: "Archive Integrity Shield" sc23219-PCBS2v1008.part2.rar
Compares the hash of your .part2.rar against a known database for version 1.008 to ensure the file isn't corrupted or injected with malware during the download. This feature would act as a pre-check script