I may have found a solution to use loose "sr3_city.lua". Here's how to do it;
- Backup "misc_vpp.pc"
- Open "misc_vpp.pc" with Hex Editor
- Search words with "sr3_city.lua" (Maybe you'll hit 0x00006E06)
- Overwrite "sr3_city.lua" with all "00" (This makes SRTTR can't read "sr3_city.lua" from "misc_vpp.pc")
- Copy "sr3_city.lua" from SRTT to SRTTR's root folder
- Run the game