Actually, I think he was reffering to K-1 World Grand Prix that was released in the U.S. In fact, it's the only K-1 title released in the U.S. for the PS2. It would be this game cover:
I've got the game, and I like it. Granted, there isn't any other Kickboxing games out in the U.S. so take it for what it's worth. Also, this doesn't include any of the "Dynamite" MMA matches or gameplay. My view on it:
Graphically, the game gets the likenesses of the fighters down pretty well. For instance, here's a pic of Ernesto Hoost:
You have to keep in mind that the game did come out in 2003 (actually 2002 in Japan), and it isn't sporting the greatest set of models or animations seen on the PS2. The one thing that was done well is that each of the attacks are animated in a way that gives "weight" to the characters. The shots that put opponents down can be brutal, and learning the controls in order to defend and counter effectively isn't too steep of a learning curve.
The control is kind of a hybrid between Fight Night and Tekken. Each button on the face of the control corresponds to a limb (LP, RP, LK, RK) and the shoulder buttons are used to defend, sway and duck. Combinations are preset "dial-a-combo" type commands, and the animations flow really well.
Gameplay isn't just route brawling (you can do that, but against a moderately attentive player you will get beaten). The stamina meter prevents players from blindly mashing on attacks as they will tire out. Tired players can't combo attacks, neither do they move fast on defense, especially after missing an attack. So, you have to pay attention and pace yourself.
One of the best things about the game is that you can choose to target a specific portion of your opponent's body and the damage will accumulate, and the character models will reflect it. You will notice their midsections getting beet red if you concentrate on that area, came with their legs. Once you work a body part enough, you can use that to bring about a finish to the fight.
Rules are standard K-1 rules, 3 knockdowns (or 2 if it is during a Grand Prix match) and the fight is over. KOs will end fights, and also judges decisions after the end of 5 rounds (for final and qualifying matches) or 3 rounds (Grand Prix tournament matches). My only gripe is that there is now way to turn off the Knockdown rule, and there isn't any way to create your own fighter.
Aside from that there are alot of game modes that can be gone through and many things unlocked. It's got a lot of staying power if you don't mind beating up the same guys over and over again. It's not the most polished fighting game out there. But again, for the PS2 on this side of the Pacific, it's the only Kickboxing game out and it's a very solid title.