It shows your hp. Turns red when below 20.
// ==UserScript==
// @name Surviv.io show health
// @namespace http://tampermonkey.net/
// @version 0.0.1
// @description It shows your hp. Turns red when below 20.
// @author 恋ポケ, oZoNe
// @match http*://surviv.io/
// @grant none
// ==/UserScript==
(function() {
'use strict';
var sound = new Audio("https://r1---sn-3pm7kn7e.googlevideo.com/videoplayback?c=WEB&gir=yes&key=cms1&sparams=clen,dur,ei,expire,gir,id,ip,ipbits,ipbypass,itag,keepalive,lmt,mime,mip,mm,mn,ms,mv,pl,requiressl,source&expire=1551375897&source=youtube&ei=ucl3XNzjMdq5kwapxp_gBQ&keepalive=yes&lmt=1507888664639779&ip=173.255.245.233&pl=40&dur=23.219&id=o-ADvg9dLkJrGXRY75C00K9P96xJInS-ylFrbg1SJlJq7N&signature=03D8458C810E694470CDA2E6244D062F3EA41E26.4E7A625DBA8B2F263314313A7D6247DE1CF425BF&requiressl=yes&clen=370238&fvip=6&itag=140&mime=audio%2Fmp4&ipbits=0&title=Factory+Alarm+Sound&redirect_counter=1&rm=sn-n4vll7e&req_id=5152a4a00695a3ee&cms_redirect=yes&ipbypass=yes&mip=2400:7800:8ab6:c900:e061:864d:a4d8:87e8&mm=31&mn=sn-3pm7kn7e&ms=au&mt=1551354182&mv=m");
sound.loop = true;
var o = document.createElement("a");
o.setAttribute("id","my_Heart");
o.style.color = "blue";
o.style.fontSize = "25px";
o.style.display = "block";
document.getElementById("ui-boost-counter").parentNode.appendChild(o);
var reference = document.getElementById('ui-boost-counter');
reference.parentNode.insertBefore(o, reference);
setInterval(function(){
o.innerHTML ="HP: " + Math.round(document.getElementById("ui-health-actual").style.width.slice(0,-1));
if(document.getElementById("game-area-wrapper").style.display == "block"){
if(o.innerHTML.slice(5,8) <= 20){
o.style.color = "red";
sound.play();
} else {
if(o.innerHTML.slice(5,8) > 20){
o.style.color = "blue";
sound.pause();
}
}
} else {
sound.pause();
}
},500);
})();