emuparadisev2.eptun.user.js

// ==UserScript==
// @name         EmuParadise download script
// @version      1
// @description  Downloads games directly after clicking their name
// @author       Eptun
// @require      http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js
// @match        https://www.emuparadise.me/*/*/*

// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    $(".gamelist").each(function(i) {
        var id = $(this).attr('href').split("/")[3];
        $(this).attr('href', "/roms/get-download.php?gid="+id+"&test=true");
    });

})();

Just FYI you could make do without jQuery.

var links = document.querySelectorAll('.gamelist')
for (var i=0; i<links.length; i++) {
    var id = links[i].href.split("/")[3]
    links[i].href = "/roms/get-download.php?gid="+id+"&test=true"
}

And you could utilize @updateURL to automatically update your users.

it changed a bit, now the id is in the 5th position

var links = document.querySelectorAll('.gamelist')
for (var i=0; i<links.length; i++) {
    var id = links[i].href.split("/")[5]
    links[i].href = "/roms/get-download.php?gid="+id+"&test=true"
}

but it stills the same idea