Wait for an internet connection then launch a minimal instance of Steam.

README.md

1. Install GCC.

2. Run the following command to compile:

   gcc -Wall -Wextra -s -mwindows -Ofast LaunchSteam.c -lWininet -o LaunchSteam.exe

LaunchSteam.c

#include <windows.h>
#include <wininet.h>
#include <libgen.h>

int main(__attribute__((unused)) int argc, char *argv[])
{
    SetCurrentDirectory(dirname(argv[0]));
    while (!InternetGetConnectedState(NULL, 0))
        Sleep(1);
    // Steam Command Line Parameters: https://developer.valvesoftware.com/wiki/Command_Line_Options
    ShellExecute(0,
                 "open",
                 "steam.exe",
                 "-silent -forceservice -no-browser -nofriendsui -no-dwrite -nocache -noverifyfiles -noreactlogin",
                 NULL,
                 SW_HIDE);
    return 0;
}