If you make a 2D game, I think reset values etc. . Or first open game with use exec, later close first game with sys_exit.
Example for my second suggestion:
function restart_game()
{
exec(GAME EXE's NAME, ""); // for start game
wait(1); // wait sometime
sys_exit(NULL); // exit previous game
}
function main()
{
on_enter = restart_game; // on enter key run function
}
