The first Kessen is a relatively simple RTS that served as a launch title for the PS2, set towards the end of the Sengoku Period in Japan. The battles are either huge, open battlefields with dozens of officers on either side, or smaller battlefields with only a handful. From a gameplay perspective there were some really neat ideas, like officers refusing to follow your orders if their morale was low (or if you told them to do something their personality wouldn't let them), officers commanding multiple groups of infantry that would engage the enemy's groups individually while the commanders stood back and watched, and the scale was impressive.

Unfortunately, for like 80% of the game, the AI was just too stupid to really serve as a threat and almost every battle could be finished by standing still, luring the enemy into your ranks, and then jumping them with everything you have. The cursor was also really slow, which made giving orders to various officers scattered around the battlefield annoying at times.

After finishing the game for the first time as the Eastern Army (the 'historical' path) you then unlock the 'what if' path where the Western Army wins, and I found the game much more enjoyable. The game starts off at Sekigahara, the "finale" of the Sengoku Period, and many of the battles afterwards feel really minor by comparison. The Western Army story however is fictional, and allowed the developers to make up whatever they wanted and the freedom shows. Many of the battles are more enjoyable, more open, and the last few are actually somewhat challenging, which was a breath of fresh air.

Overall an interesting and experimental little piece of PS2 history (it was advertised as the first strategy game for PS2) that laid the foundation for its wacky successor.