-c - Normal mode
-d - Launch in debug mode
-n - Nickname
-h - Host / IP
-p - Port
-z - The server password

system
(
"gta_sa.exe -c -n uniss0n -h 80.66.82.113 -p 7777"
)
;
// Лучше конечно ShellExecute использовать

ShellExecuteA
(
NULL
,
"open"
,
"gta_sa.exe"
,
"-c -n uniss0n -h 80.66.82.113 -p 7777"
,
NULL
,
SW_SHOWDEFAULT
)
;