What are the most aggressive Uci & Winboard engines?

I need a aggressive engine to play. Any help would be great.:)

This one is very agressive, always attacking :

http://gchess.en.softonic.com/

Thank you so much djort. That was just what I was looking for. If anyone has nay other it would great too.

1. Define "aggressive." 

2. Unless you are at least a USCF rated master I'm unable to imagine how any modern chess engine couldn't be "aggressive" enough for you. Modern chess programs (which probably excludes the prehistoric Fritz 2, but maybe not) allow you to set all sorts of parameters for how they play, as in copying the style of a famous GM, you can also change the values of pawns and/or pieces and set how many ply the program "thinks" ahead each move etc. In other words: you can customize a modern chess program to play aggressively, passively or however else you want. You can also set how much time the program has per move or per game and what rating level it plays at. I'm pretty sure any program set at FIDE +2500 rating will be "aggressive" enough for you.

3. Not all the humans you meet OTB will play "aggressively", so unless you're only going to play a PC from now on I suggest you start training for "passive" opponents as well.

SOS 5.1 is the most aggressive/attacking/human like engine I have found. It comes with Arena and can be download.

Houdini 1.5a,hands down.

Arasan is a very aggresive engine too. S.O.S. is more pawn aggresive while Arasan is tactical aggresive. Both are free. 32bit and 64bit. '11

Houdini 1.5, Firebird & Stockfish are all free I've been told they will all work with WinBoard. Houdini is currently the strongest engine around according to what I've read, someplace or other

i think shredder classic or deep shredder 12 can help you better  it's a very aggresive chess engine and if you need also a positional, tacti engine and aggresive hiarcs can help you very well and the best thing is than you can setup the level rating  you want to play. the problem is than they are comercial engines but i can shere them to you just let me know ok if you're interest.

about houdini is te most strong engine in the planet,and is very nice to see how he can defead any engine in this world  the problem of houdini  isn't very well to analize games becuase he does unhuman moves, and  you cannot handicap houdini, so that engine only is good to do tournament engines but no for train yourself with it.

Fritz 11 and 12 have personality sliders. Has anyone played around with the "King attack" slider? Does this make it aggressive and hunt the king? I keep losing to lower ranked people who relentlessly attack my king on here because I'm not use to playing aggressive players. Any help would be great.

If you keep losing to them that means you're the weaker one... Just keep on practicing my good chap. :)

I would be very interested in this.

rybka 4,thinker,arasan,gambit fruit,fritz 12,zapa mexico....these all are aggresive.if you want strong+aggresive i would recommand rybka and zappa.and one more thing...offense of an engine quite depends on the openning book.but the engines i mentioned above are attacking in nature.

My three favorites are Shredder, Stockfish, and Hiarcs, probably. I like their styles.

Who cares...Lets play honest chess!

why do you assume people use chess engines to cheat? i use them mostly to build opening theory as i have TERRIBLE positional judgement and rely on memorization of openings to compensate. recently, just memorizing 40 lines in the smith morra gambit has improved my results against the sicilian dramatically vs 10% in wing gambit, and i'm still building theory for it to learn with engines every time a new move pops up in one of my games.

one thing i think a lot of people get "backwards" in using chess engines to improve their play or analyze games is always looking for the highest rated programs to try and emulate those. i HATED fritz 6 myself even if it was the highest rated at the time when i bought it. it plays VERY passively sucking all of the initiative out of gambits so i could easily last 30 moves against it where rebel and crafty are much more direct and hard to survive 20 moves against.

i don't know just how aggressive it is, but right now, ruffian is my favorite engine studying my own games with it and a bunch of other engines as it choses the same moves as me more often than the others with SOS 5.1 & stockfish being a couple moves behind in the 4 games i studied with anmon being another move behind, but seeing the same continuations more often.

i tried most of the freeware suggestions in this thread and others, and often, allegedly "aggressive" engines made fugly moves that block rook access to open files, passive pawn moves with pieces still undeveloped, or even *gasp* move unthreatened pieces a 2nd time in retreat. fritz 6 loves to retreat like a french trench weasel. LOL

maybe i'm chosing lower rated programs that agree with my lower rated style, but as sacking a minor piece for 2 castle pawns is a favorite tactic of mine, i'd count agreeing with my preference for development and mobility as aggressive as i only seek targets.

i had serious problems trying arasan and GChess as one or both of them put spyware that made my firewall pop-up in my PC as well as turned it buggy until uninstalling them. i couldn't find a 32 bit version of firebird either.

zappa? the freeware version doesn't agree with my style much even with  the dissident settings i could make in the freeware version and glaurung and gambit fruit in particular almost always did the opposite only agreeing with me 3 & 4 times in 4 games to ruffian's 11 times, not counting the times all of the programs agreed with me.

ruffian, stockfish, SOS 5.1 & anmon are my favorites as they think the most like me and as such, aren't going to lead my opening theory into random computer chaos i can't understand like glaurung. programs that think like me are going to develop in ways i can take advantage of better in my own games than some karpov subtle mumbo jumbo that totally eludes me.

i'd like to see if i can tune my favorites to play even more for development and initiative as well as buy copies of junior and gambit tiger to add to my theory generation quiver. for now though, more often than other programs, ruffian plays my kind of aggressive with fewer computer style moves i find fugly in the extreme a lot.

why not try using engines that play more like you? test programs in your own games to see which ones see the same opportunities as you.

Chessmaster is the best to play against. You can create your own personalities the way you like. You can make the engine play very agressive or very defensive chess. You can even make it play like a crazy human, like a patzer or like Tal. I have created a player thar will often sac a piece for attack against my king.

It's a shame this guy is gone, I could have really set him up with some awesome aggressive engines. 

whats the engine?