diff --git a/04week/mastermind.js b/04week/mastermind.js
index 60e5cfa18..369f2999a 100644
--- a/04week/mastermind.js
+++ b/04week/mastermind.js
@@ -2,6 +2,7 @@
 
 const assert = require('assert');
 const readline = require('readline');
+const colors = require('colors');
 const rl = readline.createInterface({
   input: process.stdin,
   output: process.stdout
@@ -10,13 +11,26 @@ const rl = readline.createInterface({
 let board = [];
 let solution = '';
 let letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
+let youHaveWon = false;
 
+// create function to reset game after win/loss:
+let reset = () => {
+  // set board, solution, and win state boolean to their initial values:
+  board = [];
+  solution = '';
+  youHaveWon = false;
+  // generate a new solution:
+  generateSolution();
+}
+
+// print function to add items to 'board' array in order to display previous guesses, as well as generate turn count for loss detection:
 function printBoard() {
   for (let i = 0; i < board.length; i++) {
     console.log(board[i]);
   }
 }
 
+// generate random solution based on the letters array:
 function generateSolution() {
   for (let i = 0; i < 4; i++) {
     const randomIndex = getRandomInt(0, letters.length);
@@ -24,24 +38,114 @@ function generateSolution() {
   }
 }
 
+// define getRandomInt function for use in the generateSolution function:
 function getRandomInt(min, max) {
-  return Math.floor(Math.random() * (max - min)) + min;
+  return Math.floor( Math.random() * (max - min) ) + min;
 }
 
-function generateHint() {
-  // your code here
+// generate hint by displaying both the number of correctly guessed letter locations, as well as the number of correctly guessed letters are not in the right order:
+function generateHint( guess ) {
+  // split guess and solution strings into discrete arrays:
+  let solutionArray = solution.split('');
+  let guessArray = guess.split('');
+
+  // define variables to store numbers to use in the hint:
+  let correctLetterLocations = 0;
+  let correctLetters = 0;
+
+  // iterate through the solution array and check if each character of the guess matches the solution at the same position; if so add one to correctLetterLocations:
+  for( let i = 0; i < solutionArray.length; i++ ) {
+    if( solutionArray[i] == guessArray[i] ) {
+      correctLetterLocations++;
+      solutionArray[i] = null;
+    }
+  }
+
+  // iterate through arrays again to check for guess characters which match but aren't in the correct position:
+  for( let i = 0; i < solutionArray.length; i++ ) {
+    // define a variable to store the index number in the solution of each character in the guess array:
+    let targetIndex = solutionArray.indexOf( guessArray[i] );
+    // if the solution array index of the character at guessArray[i] is > -1 then the character must exist somewhere within the solution array; add one to correctLetters:
+    if( targetIndex > -1 ) {
+      correctLetters++;
+      solutionArray[targetIndex] = null;
+    }
+  }
+  return `${correctLetterLocations}-${correctLetters}`;
+  //return colors.red(correctLetterLocations) + '-' + colors.white(correctLetters) ;
 }
 
-function mastermind(guess) {
-  solution = 'abcd'; // Comment this out to generate a random solution
-  // your code here
+// made isValid function to check if the guessed letters are valid; wrote it this way so it still works if the letters array is changed:
+let isValid = ( guess ) => {
+  // define variable to store a count (4 valid letters in a guess results in validCount of 4):
+  let validCount = 0;
+  // iterate through the characters in guess:
+  for( let character of guess ) {
+    // iterate through each letter in the letters array:
+    for( let letter of letters) {
+      // if each character of the guess matches a letter within the array, add 1 to validCount:
+      if( character == letter ) {
+        validCount++;
+      }
+    }
+  }
+  // if validCount is 4, the guess is valid:
+  if( validCount == 4 ) return true;
+  else return false;
 }
 
+// create function to check if player is out of turns. i put this in its own function to simplify code later on:
+let outOfTurns = () => {
+  // if board array length is 10 then display loss message and reset the board:
+  if( board.length == 10 ) {
+    console.log( colors.bold.bgRed(`You ran out of turns! The solution was ${solution}.`) );
+    console.log( colors.blue('Try again?') );
+    reset();
+  }
+  // or else log how many turns have been taken and keep playing:
+  else console.log(`Guess again. You've made ${board.length} turn(s) out of 10.`);
+}
+
+let mastermind = ( guess ) => {
+  // solution reassignment for troubleshooting use (leave commented for normal gameplay):
+  // solution = 'abcd';
+  
+  // make guess lowercase to avoid errors caused by unexpected capitalization:
+  guess = guess.toLowerCase();
+
+  // if guess length is not exactly 4 characters, or if the guess is not valid per the isValid function, log try again message:
+  if( guess.length != 4 || !isValid(guess) ) {
+    console.log( colors.red('Try again and guess four valid letters!') );
+  }
+  // or else if the guess is equal to the solution, set youHaveWon boolean to true:
+  else if( guess == solution ) {
+    youHaveWon = true;
+    return 'You guessed it!';
+  }
+  // or else push the guess and the generated hint to the board array:
+  else {
+    let hint = generateHint( guess );
+    board.push( `${guess} ${hint}` );
+  }
+}
 
 function getPrompt() {
+  // log message to explain what to do; wrote it like this so it still works if the letters array is modified:
+  console.log( colors.bold(`--- Pick four letters between ${letters[0]} and ${letters[letters.length-1]}! ---`) );
+  // begin prompt:
   rl.question('guess: ', (guess) => {
+    // run the user's guess through the mastermind function:
     mastermind(guess);
+    // print the board which displays all guesses and hints:
     printBoard();
+    // if youHaveWon variable is true (see line 121), log win message and reset:
+    if( youHaveWon ) {
+      console.log( colors.bold.green(`You guessed it in ${board.length + 1} turn(s)! The answer was ${solution}`) );
+      console.log( colors.bold.blue('Play again?') );
+      reset();
+    }
+    // or else run the outOfTurns function (see line 98) to check for loss state or if the game should continue:
+    else outOfTurns();
     getPrompt();
   });
 }
@@ -49,7 +153,7 @@ function getPrompt() {
 // Tests
 
 if (typeof describe === 'function') {
-  solution = 'abcd';
+  // solution = 'abcd';
   describe('#mastermind()', () => {
     it('should register a guess and generate hints', () => {
       mastermind('aabb');
@@ -62,10 +166,10 @@ if (typeof describe === 'function') {
 
   describe('#generateHint()', () => {
     it('should generate hints', () => {
-      assert.equal(generateHint('abdc'), '2-2');
+      assert.strictEqual(generateHint('abdc'), '2-2');
     });
     it('should generate hints if solution has duplicates', () => {
-      assert.equal(generateHint('aabb'), '1-1');
+      assert.strictEqual(generateHint('aabb'), '1-1');
     });
 
   });
diff --git a/package-lock.json b/package-lock.json
index bd07c0e56..71548816c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -553,9 +553,9 @@
       }
     },
     "colors": {
-      "version": "0.6.2",
-      "resolved": "https://registry.npmjs.org/colors/-/colors-0.6.2.tgz",
-      "integrity": "sha1-JCP+ZnisDF2uiFLl0OW+CMmXq8w="
+      "version": "1.3.3",
+      "resolved": "https://registry.npmjs.org/colors/-/colors-1.3.3.tgz",
+      "integrity": "sha512-mmGt/1pZqYRjMxB1axhTo16/snVZ5krrKkcmMeVKxzECMMXoCgnvTPp10QgHfcbQZw8Dq2jMNG6je4JlWU0gWg=="
     },
     "colors-tmpl": {
       "version": "0.1.1",
@@ -563,6 +563,13 @@
       "integrity": "sha1-F+n5rYBceS/6OsagSctzJ9llt/4=",
       "requires": {
         "colors": "~0.6.2"
+      },
+      "dependencies": {
+        "colors": {
+          "version": "0.6.2",
+          "resolved": "https://registry.npmjs.org/colors/-/colors-0.6.2.tgz",
+          "integrity": "sha1-JCP+ZnisDF2uiFLl0OW+CMmXq8w="
+        }
       }
     },
     "combined-stream": {
@@ -1728,15 +1735,14 @@
       "version": "github:kevincolten/htmllint-cli#5901ac1f6cd612f484f40c7f4f7515f22a2ba52d",
       "from": "github:kevincolten/htmllint-cli",
       "requires": {
-        "bluebird": "^3.4.7",
-        "chalk": "^1.1.3",
+        "bluebird": "^3.5.1",
+        "chalk": "^2.3.0",
         "cjson": "^0.5.0",
         "glob": "^7.1.1",
-        "htmllint": "^0.6.0",
-        "liftoff": "^2.3.0",
-        "promise": "^7.1.1",
-        "semver": "^5.3.0",
-        "yargs": "^6.6.0"
+        "htmllint": "^0.7.0",
+        "liftoff": "^2.5.0",
+        "semver": "^5.4.1",
+        "yargs": "^10.0.3"
       },
       "dependencies": {
         "ansi-styles": {
diff --git a/package.json b/package.json
index aff08712c..57080b13d 100644
--- a/package.json
+++ b/package.json
@@ -19,6 +19,7 @@
   },
   "homepage": "https://github.com/AustinCodingAcademy/javascript-workbook#readme",
   "dependencies": {
+    "colors": "^1.3.3",
     "eslint": "^3.19.0",
     "functional-javascript-workshop": "^1.0.6",
     "htmllint-cli": "github:kevincolten/htmllint-cli",