diff --git a/app.py b/app.py
index cc155e0..c87f43b 100644
--- a/app.py
+++ b/app.py
@@ -4,30 +4,49 @@ from string import ascii_lowercase
 from flask import Flask, render_template, session, request, redirect, url_for, flash
 
 import sensitive
-from lib import cat_words, ROUNDS
+from lib import cat_words, ROUNDS, WORD_LENGTH
 from play import build_non_letter_hint, build_letter_hint
 
 app = Flask(__name__)
 app.config['SECRET_KEY'] = sensitive.SECRET_KEY
+
 WORDS = list(cat_words())
 NUM_GAMES = len(WORDS) - 1
 GUESS_SPLITTER = '|'
+
+RANDOM_GAME_ID = -1
+
+KEY_WORD = 'word'
+KEY_GAME_ID = 'game_id'
+KEY_GUESSES = 'guesses'
+KEY_GUESS = 'guess'
+KEY_STATE = 'state'
+
 STATE_PLAYING = 'PLAYING'
 STATE_WIN = 'WIN'
 STATE_LOSE = 'LOSE'
-RANDOM_GAME_ID = -1
+
+COLOR_GREY = 'grey'
+COLOR_GREEN = 'green'
+COLOR_YELLOW = 'yellow'
+
+ERROR_GAME_ID_RANGE = "game_id must be between 0 and {}".format(NUM_GAMES)
+ERROR_NEED_WORD = 'need a word'
+ERROR_GUESS_LENGTH = "Make a {} letter guess.".format(WORD_LENGTH)
+ERROR_WORD_NOT_IN_LIST = 'Not in word list: {}'
+ERROR_NO_GAME = 'No game started.'
 
 
 def init_game(game_id, word):
-    session['game_id'] = game_id
-    session['word'] = word
-    session['guesses'] = ''
-    session['state'] = STATE_PLAYING
+    session[KEY_GAME_ID] = game_id
+    session[KEY_WORD] = word
+    session[KEY_GUESSES] = ''
+    session[KEY_STATE] = STATE_PLAYING
 
 
 def resolve_guesses():
-    word = session['word']
-    guesses = session.get('guesses', '').split(GUESS_SPLITTER)
+    word = session[KEY_WORD]
+    guesses = session.get(KEY_GUESSES, '').split(GUESS_SPLITTER)
     guesses_colored = []
     for guess in guesses:
         non_letters_hints = build_non_letter_hint(guess, word)
@@ -35,13 +54,13 @@ def resolve_guesses():
         colored_guess = []
         for pos, letter in enumerate(guess):
             if letter in non_letters_hints:
-                color = 'grey'
+                color = COLOR_GREY
             elif letters_hints[pos] == letter.upper():
-                color = 'green'
+                color = COLOR_GREEN
             elif letters_hints[pos] == letter:
-                color = 'yellow'
+                color = COLOR_YELLOW
             else:
-                color = 'grey'
+                color = COLOR_GREY
             colored_guess.append((letter, color))
         guesses_colored.append(colored_guess)
     return guesses_colored
@@ -51,14 +70,20 @@ def build_game_state():
     guesses_colored = resolve_guesses()
     return render_template('game.html',
                            guesses=guesses_colored,
-                           state_playing=session['state'] == STATE_PLAYING,
-                           state=session['state'])
+                           state_playing=session[KEY_STATE] == STATE_PLAYING,
+                           WORD_LENGTH=WORD_LENGTH,
+                           KEY_GUESS=KEY_GUESS,
+                           state=session[KEY_STATE])
+
+# #############################################################################
+# ROUTES
+# #############################################################################
 
 
 @app.route('/')
 def home():
     num_games = NUM_GAMES
-    return render_template('home.html', num_games=num_games)
+    return render_template('home.html', num_games=num_games, KEY_GAME_ID=KEY_GAME_ID)
 
 
 @app.route('/init/random')
@@ -70,14 +95,14 @@ def init_random_game():
 
 @app.route('/init/deterministic', methods=['post'])
 def init_deterministic_game():
-    game_id = request.form.get('game_id')
+    game_id = request.form.get(KEY_GAME_ID)
     return redirect(url_for('init_deterministic_game_id', game_id=game_id))
 
 
 @app.route('/init/deterministic/<int:game_id>')
 def init_deterministic_game_id(game_id):
     if not 0 <= int(game_id) <= NUM_GAMES:
-        flash("game_id must be between 0 and {}".format(NUM_GAMES))
+        flash(ERROR_GAME_ID_RANGE)
         return redirect(url_for('home'))
     word = WORDS[int(game_id)]
     init_game(game_id, word)
@@ -86,43 +111,44 @@ def init_deterministic_game_id(game_id):
 
 @app.route('/random')
 def random_game():
-    if 'word' not in session or 'state' not in session:
+    if KEY_WORD not in session or KEY_STATE not in session:
         return redirect(url_for('init_random_game'))
     return build_game_state()
 
 
 @app.route('/deterministic/<int:game_id>')
 def deterministic_game_id(game_id):
-    if 'word' not in session or 'state' not in session or ('game_id' in session and session['game_id'] != game_id):
+    if (KEY_WORD not in session or KEY_STATE not in session or
+            (KEY_GAME_ID in session and session[KEY_GAME_ID] != game_id)):
         return redirect(url_for('init_deterministic_game_id', game_id=game_id))
     return build_game_state()
 
 
 @app.route('/guess', methods=['post'])
 def make_guess():
-    if 'word' not in session or 'guesses' not in session:
-        flash('need a word')
+    if KEY_WORD not in session or KEY_GUESSES not in session:
+        flash(ERROR_NEED_WORD)
         return redirect(url_for('home'))
-    guess = request.form.get('guess')
-    if len(guess) != 5 and not all([x in ascii_lowercase for x in guess]):
-        flash("Make a 5 letter guess.")
-        return build_game_state()
+    guess = request.form.get(KEY_GUESS)
     guess = guess.lower()
-    if guess not in WORDS:
-        flash('Not in word list: {}'.format(guess))
+    if len(guess) != WORD_LENGTH and not all([x in ascii_lowercase for x in guess]):
+        flash(ERROR_GUESS_LENGTH)
         return build_game_state()
-    word = session['word']
-    round = len(session['guesses'].split(GUESS_SPLITTER))
-    if round >= ROUNDS:
-        session['state'] = STATE_LOSE
+    if guess not in WORDS:
+        flash(ERROR_WORD_NOT_IN_LIST.format(guess))
+        return build_game_state()
+    word = session[KEY_WORD]
+    round_i = len(session[KEY_GUESSES].split(GUESS_SPLITTER))
+    if round_i >= ROUNDS:
+        session[KEY_STATE] = STATE_LOSE
     if guess == word:
-        session['state'] = STATE_WIN
-    session['guesses'] += '{}{}'.format(guess, GUESS_SPLITTER)
-    if 'game_id' not in session:
-        flash('no game_id')
+        session[KEY_STATE] = STATE_WIN
+    session[KEY_GUESSES] += '{}{}'.format(guess, GUESS_SPLITTER)
+    if KEY_GAME_ID not in session:
+        flash(ERROR_NO_GAME)
         return redirect(url_for('home'))
-    game_id = session['game_id']
-    if game_id == -1:
+    game_id = session[KEY_GAME_ID]
+    if game_id == RANDOM_GAME_ID:
         return redirect(url_for('random_game'))
     return redirect(url_for('deterministic_game_id', game_id=game_id))
 
diff --git a/templates/game.html b/templates/game.html
index cd2a8cf..d7b4261 100644
--- a/templates/game.html
+++ b/templates/game.html
@@ -13,7 +13,8 @@
     </ul>
     {% if state_playing %}
         <form method="post" action="{{ url_for('make_guess') }}">
-            <input maxlength="5" minlength="5" size="5" name="guess" autofocus autocomplete="off"
+            <input maxlength="{{ WORD_LENGTH }}" minlength="{{ WORD_LENGTH }}" size="{{ WORD_LENGTH }}"
+                   name="{{ KEY_GUESS }}" autofocus autocomplete="off"
                    style="text-transform:uppercase"/>
             <input type="submit">
         </form>
diff --git a/templates/home.html b/templates/home.html
index 8c725a4..f438ed5 100644
--- a/templates/home.html
+++ b/templates/home.html
@@ -3,7 +3,7 @@
 <a href="{{url_for('init_random_game')}}">Random game</a>
 <form method="post" action="{{url_for('init_deterministic_game')}}">
     <label>Deterministic (0 to {{ num_games }})</label>
-    <input type="number" min="0" max="{{ num_games }}" name="game_id" autofocus/>
+    <input type="number" min="0" max="{{ num_games }}" name="{{ KEY_GAME_ID }}" autofocus/>
     <input type="submit">
 </form>
 {% endblock %}
\ No newline at end of file