only pick words of 15 and shorter

src/Game.cpp

@@ -104,8 +104,10 @@ Game::Game() :
     for (int i = 0; i < words_len; i++)
         all_words.push_back(words[i]);
     std::shuffle(all_words.begin(), all_words.end(), rng);
-    word = all_words.back();
-    all_words.pop_back();
+    do {
+        word = all_words.back();
+        all_words.pop_back();
+    } while (strlen(word) > 15);
     guess_corrector = std::make_unique<GuessCorrector>(word);
     std::cout << "Word: " << word << std::endl;
 }