Currently the main site is used mostly by community who create/post puzzles and write answers to them. It is possible to use the site just to solve puzzles and to check solutions against existing answers, and some users including me are trying to use it this way. I believe great many users could potentially use it this way, much more users that currently using this site. However for the most of those potential users the puzzles are too difficult, so if they try, they are likely to give it up soon. Also the existing community fray upon easy puzzles. Also there were several suggestions on this meta to mark the puzzles by difficulty, which would benefit those potential users, but the suggestions were rejected by the existing community, because "difficulty is subjective" and "no one needs it".
I suggest one of three possible alternative solutions addressing the problem of difficulty. The first is better, the second is easier to implement, the 3rd is very easy to implement.
Each answer contains two fields instead of one: "formal answer" and "full answer". Formal answer is for future computer-checking. Formal answer would normally be short for example "102.564" or "6 7 8" or "elephant". Another user who tries answering the puzzle later could test his guess of formal answer against the existing ones - there would be a box under the puzzle to do just that. A user could try multiple guesses. There also may to a button
show the answers. After clicking
show the answersone would not be able to try more guesses of the the formal answer. Hidden texts in the existing answers would be shown only after a correct guess of the formal answer or after clicking
show the answers. All guesses would be anonymously recorded and statistics from that could be used to objectively calculate difficulty (% of people whose first guess was the correct one)
We add one checkbox beside every existing answer
[x] this was my first answer as well. Any user would be able to check this checkbox. Other users will not see, what checkbox this particular user checked, however the statistics would be available for everyone. The statistics would be used to estimate the difficulty of the question (% of people whose first answer was the correct one).
Just introduce tags "easy", "intermediate", "hard" etc.