Prolog lab - game playing part

% temporary knowledge base
w('cat').
w('dog').
w('monkey').
w('frog').
w('reindeer').

replace(Word, Asterisks, Char, OutputAsteriks) :-
    replace(Word, Asterisks, Char, OutputAsteriks, []).

replace([], [], _, TempOutputAsterisks, TempOutputAsterisks).

replace([WordHead | WordTail], [_ | AsterisksTail], Char, OutputAsteriks, TempOutputAsterisks) :-
    WordHead = Char,
    append(TempOutputAsterisks, [Char], TempOutputAsterisks1),
    replace(WordTail, AsterisksTail, Char, OutputAsteriks, TempOutputAsterisks1), !.

replace([_ | WordTail], [AsterisksHead | AsterisksTail], Char, OutputAsteriks, TempOutputAsterisks) :-
    append(TempOutputAsterisks, [AsterisksHead], TempOutputAsterisks1),
    replace(WordTail, AsterisksTail, Char, OutputAsteriks, TempOutputAsterisks1).


create_asterisks(0, []).
create_asterisks(Length, List) :-
    Length1 is Length - 1,
    create_asterisks(Length1, List1),
    append(['*'], List1, List).


compare_words(Chars, Asterisks) :-
    atomics_to_string(Chars, WordString),
    atomics_to_string(Asterisks, AsterisksString),
    WordString = AsterisksString.

get_word(Chars, Asterisks) :-
    bagof(X, w(X), Words),
    length(Words, Length),
    random(0, Length, RandVal),
    nth0(RandVal, Words, Word),
    atom_chars(Word, Chars),
    length(Chars, WordLength),
    create_asterisks(WordLength, Asterisks).

play :-
    get_word(WordChars, AsterisksChars),
    atomics_to_string(AsterisksChars, AsterisksString), write('\nPlease guess the word: \t'), write(AsterisksString),
    main_loop(WordChars, AsterisksChars, 0).

% base case (words match)
main_loop(WordChars, AsterisksChars, GuessesCount) :-
    % if it is the same
    compare_words(WordChars, AsterisksChars),
    write('\nCongratulations! It only took you '), write(GuessesCount), write(' guesses.'), !.

main_loop(WordChars, AsterisksChars, GuessesCount) :-
    write('\nPlease guess a letter:\t'), get_single_char(AsciiCode), atom_char(Char, AsciiCode), write(Char),
    GuessesCount1 is GuessesCount + 1,
    replace(WordChars, AsterisksChars, Char, OutputAsteriksChars),
    atomics_to_string(OutputAsteriksChars, OutputAsterisksString), write('\nYour soultion: \t\t'), write(OutputAsterisksString),
    main_loop(WordChars, OutputAsteriksChars, GuessesCount1).