...and now I am plunged into a moral quandary.

Basically, I was playing a team match ("online", not live)against a free member from Russia, and we followed a recent line from the database (Novak-Mohr 2008) all the way to the end, when he resigned (correctly).

I had never had access to a database until I got the premium membership here, and had never played correspondence-type chess at all.  In hundreds of games to this point, everyone had deviated at some point, and many had access to the database themselves, so it was sort of an enjoyable mini-game jockeying around for the better opening position with roughly equal knowledge.  And when someone goes out of book, you can compare it to the master move and try to figure out why the other guy's move is (presumably) flawed.

But just kind of riding the dude to his doom started to feel a little weird around the twelfth move (this wasn't some scholar's mate elaboration or anything- it was technically a miniature, but went almost 20 moves long).  It felt like cheating, in a way even more than using an engine because at least in that case some agent is "thinking".  Kind of reminds me of Kasparov's comment after his match losing opening error against Deep Blue that a "game" had not properly even occurred since his move order error and its correct demolition were well known to theory, so there was no real opportunity for original thought.

Of course, I could have just deviated at some point, but I understood the point of "my" moves and didn't feel like sabotaging myself just to save the other guy from his foreordained beat down.  Besides, when?  I really didn't believe that he would follow the line every move.

I guess it's no big deal, but it does kind of suck that the dude mirrored the play of a master (2235) in order for that to even happen to him.  In the end, I sent him a trophy and came clean, citing the game, and the analysis I ran on the chess.com computer afterwards.  I haven't heard back.  What do the moral philosophers of the chess.com community think?  Cheesy?  Mean?  Who cares?  Has this ever happened to anyone else?   

Who cares, I think.

Even OTB I have followed Master games I have memorised (mostly traps, admittedly) to resignation or even mate.

A few years ago (I think) a guy posted here a game where he put in conditional moves from move 1, right up to the smothered mate trap in the Budapest Gambit.

On this site I have followed Mieses-Chigorin Vienna Game to mate multiple times.

In the 1930's Dake fell for a really cheap trap in the Alekhine, must have repeated that game 10 times on this site.

So, I say, so what!

I posted a similar thing here today, and I try to deviate early for that reason, without losing too much of an advantage. Then you really see who can play. Otherwise its a sham

http://www.chess.com/forum/view/general/using-game-explorer

Years ago(many) i would play book 10/12 moves and then go my own way. Here is what an old chess player now believes. No tech,computer/engine.No playing someone's opening line unless each move is make w/ my ideas.Don't worry about a rating(yours or opponent)number. There are people who play much better and worse,so enjoy and have chess fun....positions -tactics are fun for me(well i am weird). Probably he was rated lower then u? He went along w/ the game because he was playing high level chess ? Would u repeat the same theme  as the game loser....thats my answer to your moral question. Good luck

I use explorer (or rather, my own DB) when I try to learn a new opening, or line.

Like, a month or 2 ago I became vaguely interested in the Sicilian wing gambit, and used explorer to help me through a few games. I decided I didn't like it, and went back to what I always played.

So, it's kinda handy if you want to try out stuff without putting in a lot of effort first.

For most of us, correspondence chess is "training wheels" chess.  It allows us opening "expertise" that helps get us into "real" chess positions.  As a tradeoff we accept a certain artificiality in the game such as you have experienced.  I too have felt vaguely "unclean" after a win such as you described.  I played a Najdorf poisoned pawn against another patzer and it was ridiculous.  We played to the end of "book", he made a bad move that I recognized from a Chess Mentor lesson (augmented by a GM Shankland video) and was able to capitalize on.  Is that chess?  No, it just proved that I had better resources than my opponent.   Did I feel bad?  Oh a little bit, but then I reminded myself about the "training wheels", and I was OK with it.

It used to happen fairly often in the days before computer databases and internet distribution of games from open tournaments all over the world.  It used to take time to even get the games from some GM events, so games with opening refutations were sometimes repeated because few players had seen them.

It is less usual now, but if he walks into it how is it any different than walking into any other opening trap?

 There are gray lines no doubt. Do u reproduce things u read or someones invention as YOURS. It's what u know and personal beliefs.Too repeat an opening that u do not understand in a chess theory sense is imitation or parroting another. If your in a differcult chess position why not check in w tech. and get the "correct response", or call a friend rated 2500 ? It will work but u will have no idea why..... Training wheels are fine for learning---u grow up, remove wheels and rely on yourself.

For what it's worth, the guy just replied and seems okay with it, though he speaks only Russian and apparently the translator utility he was losing didn't fully get across what I was trying to say.  But the gist seems to have been intact.

If it was wrong to use it, the feature wouldn't be there. Simple as that, really.

People follow popular opening lines for 25 moves, all of which were discovered, analyzed, and refined by someone else.  How is this different?

In every single discipline of knowledge and research, we build on what was discovered before by others.  How is this different?

@OP: You used a tool that was available to you and used legally according to the site's rules. In my opinion, you committed no wrongdoing. Your opponent now knows that master game and may learn from it.

Your correct, all are climbing on the shoulders of those before them.They went to school, or learned the ins and outs of what they were doing.Here people are playing a chess game that arose from a database.Both followed a game 20 moves deep to the end. The man who lost had no chess idea of his moves because the outcome is known,----so why do it ?

BTW, all other considerations aside, the game under question was rather pretty, so here it is, with some comments on the analysis engine's evaluations:

All in all, the guy played well, and it's a pity it turned out so poorly for him.

You should do what makes you happy. If that means playing a bad move on purpose, do that. If it means copying every move, then do that! Life is too short to be pitying a chess game...

It's not cheating according to chess.com rules, as you are allowed to use databases to as full of an extent as you like. It's as simple as that.

Whether or not winning this way satisfies you is a matter of opinion.

I agree with Rhino.

well think about it in this sense... if you cant remember it in a tounement and you're playing a rated game then you're cheating unless you agree with your opponent to get to that position. your rating should reflect your skill, this is important not to abuse the honesty of your oppenent. its called sportsmanship

Looking at the game, it's very doubtful he chose white's moves randomly. He was probably familiar with the game too and hoped you weren't.

Apparently, ignorance isn't bliss. 

On a related matter, Aronian lost to Anand who had previously studied the game on his computer. A few months ago, Giri beat Radjabov in a line he had prepared using several chess engines after he had memorized a game that van Wely had played against Radjabov in the same line.

Don't feel guilty. You played within the rules of the game and won. 

Be aware that your opponent can go back and analyse that game and find some killer improvements for the next time you play him!

Congratulations!

You are talking about following a line for 20 moves! I can't play 5 moves without doing something weird (read: stupid) 

I agree with most everyone, that you did the right thing and won the game. I disagree with baddogno about correspondence chess being training wheels chess. To me, correspondence chess is about preperation. Use your best database to give you a good position once your opponent varies, so that you can win the game from there. Or study games to find novelties, like Kasparov was famous for. It is extremely rare that 2 chess games will be exactly the same.

As for your opponent's feelings, either, asSmyslovFan said he was waiting for you to deviate and messed up, in which case he doesn't feel too bad; or he did not know the game and can say to himself, "I lost, but I played the same moves as a Master."