Melee combat system

Zeno Clash is a first-person game focused on melee combat. It's great.

Oni - the best mixture of melee and pew pew. Pretty old, not on Steam but if you really want something good you can find it.

Risen 1, if you are looking for an excellent melee combat system in a RPG game.

Mount and Blade: Warband is excellent.

Blade of Darkness!!!

any of the hl series

Mount and blade series

Condemned

Devil May Cry 4, ignore the whiners, it's an excellent game despite a few flaws. Stay away from Devil May Cry 3, its PC port is a mess. The PS2, PS3 and X360 versions are good.

play street fighter 3rd strike, that game is very technical with the parry system

Saints Row the Third. You can beat people up with a dildo in that game.

Kingdoms of amalur

I always found Ninja Gaiden (the first 3D one for Xbox, I didn't play the sequel but I heard that was good too) to have some of the most satisfying melee combat ever. It's partially because of the relatively high difficulty which means every move counts and makes victory all the sweeter, and partially because of the way combat flowed naturally and felt just right. Really made me go YES, I AM A SUPER NINJA when I finally started getting good at it.

If you're looking at something more like Dark Messiah, I recommend Mount&Blade. It's a bit clunky compared to more actiony games like Ninja Gaiden or Devil May Cry, but it's more realistic and super satisfying once you get the hang of it. Not to mention that you get to lead your own army and fight among your men against rival armies, which is just cool as hell. Whether you choose to PEW PEW at your enemies with a bow, slaughter them with a sword or ride them down on horseback, it's just a really nice game.

dead island

OVERGROWTH(Alpha)!!! Procedural animation rox

Prince of Persia trilogy (Sands of time, Warrior within and Two thrones) especially the last two games.
Haven't enjoyed melee combat in any game more than in those.
Warrior Within free form fighting trailer
Two thrones use the same system, but obviously improved with more variations (chain ftw).

Lugaru HD had one of the quickest combat systems ever to be invented. It kicks butt, rabbit butt.

Viewtiful Joe. I'd pay in blood, my own or that of any other, just to see another game in that series.

God Hand from PS2... the re-invention of the Beat'em up; build your own combo
Bloodrayne games are great, you have a strong melee based action + acrobatics (in the 2nd one) and some shooting, but is lock-on based

Try Rusty Hearts, is F2P MMO Action RPG, not lock-on based, game-pad compatible, really fun

s4league ^^

Obviously fighting games win here. No question. SF, KoF, Tekken, VF, Skullgirls...whatever your choice.

If you were talking about melee fighting in non-fighting games, then it's a toss up between Mount & Blade Warband and Jedi Knight: Jedi Academy.

I really enjoy AC:Brotherhood, but that's not a "fighting system" as much as a "kill system".

Chronicles of Riddick Games, hands on.

Really simple, yet extremely satisfying, and shotting scenes were also very well done, not something common to see nowadays.

knights of the temple

devil may cry 4, I think it was pretty fun, it's been too long though. I really liked smashing zombies in the face in left 4 dead 2. And bioshock 2, the arm drill.

Deus Ex... All games.