diff --git a/static/ortie.js b/static/ortie.js
index eba546b..b3cebec 100644
--- a/static/ortie.js
+++ b/static/ortie.js
@@ -23,6 +23,28 @@ async function updateTarget() {
     console.log("ready!");
 }
 
+const levenshteinDistance = (str1, str2) => {
+    const track = Array(str2.length + 1).fill(null).map(() =>
+    Array(str1.length + 1).fill(null));
+    for (let i = 0; i <= str1.length; i += 1) {
+       track[0][i] = i;
+    }
+    for (let j = 0; j <= str2.length; j += 1) {
+       track[j][0] = j;
+    }
+    for (let j = 1; j <= str2.length; j += 1) {
+       for (let i = 1; i <= str1.length; i += 1) {
+          const indicator = str1[i - 1] === str2[j - 1] ? 0 : 1;
+          track[j][i] = Math.min(
+             track[j][i - 1] + 1, // deletion
+             track[j - 1][i] + 1, // insertion
+             track[j - 1][i - 1] + indicator, // substitution
+          );
+       }
+    }
+    return track[str2.length][str1.length];
+ };
+
 function isLetter(str) {
     return str.length === 1 && str.match(/[a-z]/i);
 }
@@ -30,6 +52,11 @@ function isLetter(str) {
 updateSpellField = (text) => {
     field.innerText = text;
     field.style.color = "";
+
+    if(text.length == 0) {
+        field.innerText = "escribe algo...";
+        field.style.color = "gray";
+    }
 }
 
 updateScores = () => {
@@ -41,11 +68,15 @@ updateScores = () => {
 }
 
 submitBuffer = () => {
-    if(buffer.toLowerCase() !== target.toLowerCase())
+    let distance = levenshteinDistance(buffer.toLowerCase(), target.toLowerCase());
+    if(distance > 1)
     {
         updateSpellField(target);
         field.style.color = "red";
         failedAttempts += 1;
+    } else if(distance > 0) {
+        updateSpellField(target);
+        field.style.color = "yellow";
     } else {
         updateSpellField(buffer);
         field.style.color = "green";
@@ -64,6 +95,11 @@ document.onkeyup = (ev) => {
         {
             if(buffer.length != 0) submitBuffer();
         }
+        if(key === "Backspace")
+        {
+            buffer = buffer.slice(0, buffer.length - 1);
+            updateSpellField(buffer);
+        }
         if(isLetter(key))
         {
             buffer += key;