wonder of wonders, I managed to fix it myself. just changed a "maxlength=7" to "maxlength=8" or something like that, and it worked!
here's the text of the edited script, don't know how to host it or make it "installable" but if you edit the user script to this, it will work next time you start firefox... (do not include the ============================='s )
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// ==UserScript==
// @name Game Jump
// @namespace
// @description Insert a game number and this script takes you there!
// @include
http://www.conquerclub.com/*// @include
https://www.conquerclub.com/*// ==/UserScript==
var li = document.createElement('li');
li.innerHTML = "<span style=\"\" class=\"divider\"><input maxlength=\"8\" style=\"font-size:1em;width:145px;padding:0em;text-indent:0.1em\" value=\"Insert Game #\" onfocus=\"if (this.value == 'Insert Game #') this.value = '';\"id=\"gamenumber\" type=\"text\" /></span>";
var ul = document.getElementById("leftColumn").getElementsByTagName("ul");
ul[0].appendChild(li);
document.getElementById('gamenumber').addEventListener('keypress', function(event) {
if(event.keyCode == 13) {window.location.href = window.location.protocol + "//www.conquerclub.com/game.php?game=" + document.getElementById("gamenumber").value}
}, false);
document.getElementById('gamenumber').addEventListener('keypress', function(event) {
event.stopPropagation();
}, false);
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