The Delfi Engine - Rest In Peace, My Friend

FYI, much of this post was previously mentioned in a past Chessmaster thread, but because it was buried in that thread, I decided that the Delfi engine deserves its own thread. That past Chessmaster thread is here:

https://www.chess.com/forum/view/chess-equipment/chessmaster-gm-edition-personalities

Imho, the two most natural-playing engines are HIARCS and Delfi. The HIARCS engine is a commercial engine that's still being offered as a part of the Chess Explorer GUI. It serves as a decent analysis engine, and it's great as an engine for people to play against. The commercial Delfi engine did not have Multi-PV capability, and it wasn't super strong. As such, it wasn't well suited for engine analysis. Its main purpose was as an engine for people to play against.

The Bad news - However, it seems that the commercial Delfi engine is no more. If you go to the Delfi web site ( http://www.msbsoftware.it/delfi/ ), you'll notice that the engine can no longer be ordered.

The Good News - The Delfi author also offered a free version of the engine that was restricted in its elo range. If buying the HIARCS Chess Explorer isn't an option for you, the free versions of the Delfi engine are a possible solution to get a fairly natural engine to play against, as long as your rating isn't much over, say 1800 elo.

Here are the important free versions of the Delfi engine that are still available:

The Delfi 5.4 UCI demo engine only runs at either 1000 elo or full strength. You can still get it here: http://www.msbsoftware.it/delfi/

The Delfi 5.0 WB demo engine can be set between 1250 elo and 1550 elo. You can get it either here:

https://web.archive.org/web/20130516190555/http://www.top-5000.nl/dl/delfi.zip or here:

https://web.archive.org/web/20070208171602/http://www.msbsoftware.it/delfi/

The Delfi 4.5 WB demo engine can be set between 1250 elo and 1700 elo. It's still available as part of a free Winboard X/Rybka package. (Extract the Delfi files from the Winboard X archive file.) You can get it here:

https://web.archive.org/web/20120604090850/http://files.chesscomfiles.com/download_files/614/Portable_WinboardX_Rybka.zip

The Delfi 4.5 engine is perhaps 150 elo stronger than the other two Delfi engines. If you download all three engines, you can get strengths of 1000 elo, and between 1250 elo to about 1800+ elo (factoring in the stronger performance of the ver 4.5 engine). The switchover point between the ver 5.0 engine and the ver 4.5 engine is around the 1425 elo level of the ver 5.0 engine. That is, for the weakest range, use Delfi 5.0 elo levels from 1250 to 1425. For stronger play, switch to Delfi 4.5 elo levels 1250 to 1700.

For the two WB engines, you need to specify the elo level in the Delfi.ini file.

I think I downloaded the 5.1 open source version today.

http://www.msbsoftware.it/delfi/source.htm

How is 5.1 open source bad? Is 5.4 that much better?

By the way, I think you write great guides. Whenever I look up stuff about engines you show up. Awesome work, man.

I also noticed that the 5.1 source code is available, which could be interesting if you're a programmer (I'm not). If you open up the source code, you'll even notice that he included the engine executable. The only problem is that neither the executable nor the source code includes the code for the easy levels. So even if you were to compile the source code yourself (I actually did that), the engine will only play at full strength (and maybe also at 1000 elo, I don't remember).

I'm just thankful that I bought a copy of 5.4 when it was available, but that doesn't help anyone who would like to buy a copy now. At least for those people, HIARCS is available for purchase.

@EscherehcsE What is the difference between your purchased copy of 5.4 and the downloadable delfi.zip which I believe is also 5.4?

The current downloadable version 5.4 only runs at settings of full strength or 1000 elo, whereas the purchased copy of version 5.4 will run at settings of either full strength, or anywhere between 1000 elo and 2300 elo.

With my purchase, I received the UCI engine file, which can be installed into any GUI that can run a UCI engine, and I also received the "2.5D Delfi GUI", which can be used to play Delfi in the 2.5D GUI, or practice tactics in the 2.5D GUI, if you load your own tactics set into the GUI. Here's a description of the GUI: http://www.msbsoftware.it/delfi/

@EscherehcsE hey! I was wondering what do you mean by "load your own tactics set". Like what?

By the way, is Hiracs really human-like at all its levels? even its strongest?

The registered Delfi GUI will use any tactics set in either pgn or epd format. You can scrounge one up any way you can, or you can make your own.  I took a tactics book that I liked and manually created a pgn file for every tactic in the book. It only took me...a darn long time! However, I really never used the Delfi GUI for this very much. I prefer to use Fred Mellender's free YATT program (Yet Another Tactics Trainer).

Regarding HIARCS, I don't know - It seems to play very naturally at my level, but I don't have the expertise to know about the really strong levels.

yes i is a delight to play against delfi engine

Maybe a too late response but I was able to order a Delfi trainer 5.4 license recently. It's available only on request, after writing Fabio Cavicchio by email.

For this I used the mail link given on the still available Delfi homepage:
http://www.msbsoftware.it/delfi/

Then Fabio sent me a link for payment, a zip with Delfi 5.4 and my registration. So if you are interested, give it a try.

I guess reports of its death were slightly exaggerated...It's good to hear that it can still be obtained with a little effort. The registered version is definitely more convenient than messing with all the archived free versions.

The free version of Delfi 5.4 sounds quite interesting and may be exactly what I have been looking for in an engine, especially if it has only limited strength.

I wish that older and abandoned chess engines would be open-sourced just as it was among the computer science community back in the 70s. Sadly, capitalism has learned to not let another Rybka-copied-code-from-Fruit scenario to happen again.