Chess Engine Review: Rebel 13/Prodeo 2.0

When it comes to chess engines, many of you will know  that my preference is strongly in favour of engines with a “human-like” style, over the raw strength of giants like Stockfish, Komodo and co.

Sure, I use Stockfish and Komodo for analysis on occasion as truth finders, but for training games or model mining I prefer engines which when seeing their play over the course of the game, I quickly say to myself “wow, this game/move could easily have been played by a human”.

I also like to play training games with engines that when they sacrifice material, I can still question the soundness of the sacrifice (as we do against human opponents), rather than just having to accept that I am lost.

Not many engines reach this level of “humanness”, but Ed Schröder has always been a programmer I admired for his ability to do just this.

His engine which started as Mephisto in the 1980s (and over the course of decades evolved into a commercial incarnation named Rebel and then finally when Ed retired into a free engine named Prodeo) plays in a very human-like positional style, with decent endgame play and also has “personalities” (these can be chosen in the settings) which change its style, sometimes dramatically towards aggressive attacking play, solid defensive play and more.

Experimenting with these is so much fun when you have a few hours to kill, I can tell you.

So when I heard that Ed had released a new engine and had named it Rebel 13 (AKA Prodeo 2.0), I couldn’t wait to get my hands on it.

Within a few minutes I’d downloaded and loaded it up in Arena 3.5 in some practice games against other engines to get some first impressions.

First Impressions:

My first impressions of the engine were not so good to be honest.

I seen it lose a brilliancy to what I thought was a Cannon-fodder engine (Ufim 8.02 is 2539 at CCRL) and started to wonder what was going on.

I’d had high hopes for this engine. 🙁

Let’s have a look.

Rebel 13 vs Ufim 8.02

In this game, Rebel seemed to play the opening horribly and get a worse position without play, and so Ufim simply applied pressure and then started sacking all over him.

I was not happy although definitely a little impressed by Ufim’s crisp attacking play.


I then kept flicking through more games from the database (I’d left the engine tournament running overnight) and seen some other games which showed more closely what Ed was trying to get at with his dramatic (seemingly) tweaks to this engine.

I believe Ed made some serious tweaks in how Prodeo handles its evaluation of passed pawns (I have no programming knowledge and can only judge as a reasonably strong chess player) and witnessed quite a few games where it sacrificed a piece and dominated its opponent with the strength of its passed pawns.

Here’s one example:

Rebel 13 vs AnMon 5.07

Yes I know that AnMon is quite a weak engine, but it has also been described as a human-like engine in its playing style, plus I like to use cannon-fodder engines as opponents to get a glimpse of a new engine’s style.

Here, Rebel reveals some of Ed’s new ideas and I must admit that when I first seen 31.Rxa5!? I was thinking “Bullshit, white is gonna get nothing for that piece”, then slowly but surely, white’s finely placed rook on the 7th rank supported the passed pawns up the board to victory. Very interesting.

So after a not-so-thorough investigation, it seemed to me that Rebel 13 was redesigned to play in an even more positional and human-like way, with extra knowledge of passed pawn play.

It is slightly weaker objectively than previous versions of Prodeo, but has a more attractive playing style which for people like me, is a big plus.

You know, the average rated chess player (this is also about 80% of all players) is rated between 1300 and 1500, so what difference does using a 2700 rated engine, a 3200 rated engine or Rebel 13 (which has just been rated at CCRL at 2653) make?

The most important thing is style and so many people forget this when spouting bullshit like “Rebel 13 is nothing special…it still loses to Stockfish”.

These are usually the same people who could look at a game played like Stockfish and understand absolutely nothing…but all they look at is the ratings.

Stick to style people…I’m telling you this is what is most important and also most interesting.

Consider the following.

I also tweaked Rebel 13 and added some of the old “personality” files (complicated, but worthwhile) to it and THAT is when things began to REALLY impress me.

Rebel started hammering engines rated over 2900, almost immediately!

Let’s have a look at a few.

Rebel 13 MACHEID

Macheid is a personality tweaked by a guy named Christian Bonnin back in the old Rebel Century days, and even Ed himself said that these old personalities don’t work very well with modern Prodeos.

That didn’t stop me trying, of course.

In the game below Macheid shows its beautifully attractive attacking style and makes the 2924 rated SmarThink 1.70 look really bad. A nice example of crisp, and clean attacking play.

Quite a drastic style difference from the plain Rebel 13, right?

Now let’s consider the amazing ALEXAL personality.

This one plays arguably more brilliant than MACHEID, but still chops down super strong opponents.

When you see the games of ALEXAL you’ll be shocked by the “intelligence” in this engine.

The way it keeps the initiative, throws away material and burns bridges in its quest to checkmate the enemy king.

Again, Rebel 13 plugs in beautifully to the ALEXAL personality. Have a look at some examples.

SmarThink 1.70 (2924) vs Rebel 13 ALEXAL

In this game, we see poor old SmarThink getting completely crushed again by Rebel 13, but this time our friend the ALEXAL personality.

Here ALEXAL plays an overwhelming attack against another very nice attacking engine, Gothmog.


Could the above games have been played by a strong human? Yes!

Were the attacks 100% sound? Who knows and who cares!

As the great programmer Chris Whittington once said:

“If you just want the normal computer-like engines to play boring (and perfect) engine vs engine matches…why not get a fish tank instead?”

Haha I agree with this and take my hat off to Ed Schröder for a great new engine, but must admit that although the new base engine Rebel 13 is great, I much prefer the chess played when using the old personality files with Rebel 13.

I’ll leave you with some more games and highly recommend you give this new engine a try.

You can download Rebel 13 from: rebel13.nl

 

UPDATE: 17th June 2016

Hey guys, here’s some stuff to make getting started with Prodeo easier. 😉

  1. Download my ENTIRE Prodeo pack (pre-added and tweaked personalities)
  2. How to Configure Personalities in Prodeo