What hides between Shadow and Light?

[Calmflow]

Umbra: The darker shadow, a total Eclipse
Penumbra: The lighter shadow, partial eclipse
These names are the same whether it is a Solar or Lunar Eclipse
"The Moon casts a dark shadow upon the Earth" speaks of a Solar Eclipse.

Fibonacci numbers are expressed in nature (one of many ways) through his Rabbit experiment.
Perhaps the hole digging creatures referred to in the anagram sentence are Rabbits?

Found this in the page source below the hints, note the part that says: name="answer"
I'm not a programmer so i don't know how all this works but to me it looks like it says that the name of the game is the answer we seek.

<div id="containerForm">
<form action="checkentry.php" method="post">
<input type="text" name="answer" size="24"/> &nbsp; &nbsp; <input type="submit" value="Submit"/>

</form>
</div>