I like it. The Character digging animation is surprisingly good. I haven't found any relics tho. Speaking of which, I made a game named "relic hunter "too. Most likely like a 100 other dudes too ^^
For the focus loss problem, try to add an onclick handler to the canvas, that calls something like:
function refocus_myself(){
var mycanvas = document.getElementById('3darea'); // or however your canvas is named
mycanvas.setAttribute('tabindex','0');
mycanvas.focus();
}