Is it even an anagram if you can use the letters multiple times? If so, then solve this. "the quick brown fox jumps over the lazy dog" It uses all letters of the alphabet. You can write an essay to solve the anagram. Or am I missing something.
The guessing game, since there's really to many possibilities if you can reuse letters. Just keep it an anagram game, but remove the use of reusing letters. you need something like "nag a ram" which is an anagram for anagram. Uses all the letters, makes sense, and doesn't leave out anything.