https://rathena.org/board/files/file/3968-verifiy-client-files-and-fix-it/
an application that check the files you want to check and download if they are missing or corrupt
this program in C# , Visual Studio 2017 , and need .Net 4.5 (you can lower the version if you put some work in to it)
it's just a template for now , so please edit it before you use it
you better not add the data.grf and rdata.grf as files as the player better just redownload the full client again
do not add your custom.grf as you will edit it every update , unless you are planing to generate new information file every update
same thing for your .dat from Thor Patcher don't add it
if you have custom.grf that you will never change with the updates , you can add it i would recommend that
this to do list i may or may not do it , however you are free to do it your self!
Encrypt information.txt
Compress uploaded files and decompress after download
add more design to the app
designing in visual studio is very easy!
after building you should encrypt your exe , but you can use it as it is (i don't suggest that).