While Onimusha Tactics delivers the familiar look and mechanics of other strategy RPGs, it doesn't have the same level of depth.
Based on Capcom's popular series of demon-slaying samurai action adventure games, Onimusha Tactics combines the premise, theme, and characters of that series with gameplay similar to other strategy role-playing games such as Final Fantasy Tactics Advance or Tactics Ogre: The Knight of Lodis. That's a recipe for success if ever there was one, but while Onimusha Tactics delivers the familiar look and mechanics of other strategy RPGs, it doesn't have the same level of depth. It can be a challenging game, but that challenge mostly comes from having to slug it out through many battles against increasingly strong foes, rather than from having to make complex tactical decisions during those battles.
Onimusha Tactics shares the same story as all the games in the series: The evil warlord Nobunaga has risen from the dead and is ransacking feudal Japan in a vengeful act against the living. He commands armies of genma, Japanese demons that take the form of the living dead, as well as other, more terrible incarnations. Most resistance against Nobunaga is summarily squashed, but one man, Onimaru, stands a chance of vanquishing this evil threat where others have failed. In the first few minutes of the game, Onimaru is told that he is descended from a clan destined to vanquish the genma, and he quickly accepts his destiny--along with a gauntlet that can absorb genma souls. Thus begins Onimaru's series of battles against Nobunaga's forces. The game is organized as a linear series of "episodes," each one revealing a bit of the game's storyline and serving up a fight pitting Onimaru and up to seven of his cohorts against a gaggle of genma.
In between episodes, you'll automatically proceed along a world map to your next destination. Initially you have no options but to save your progress or begin the next battle. Later, though, you'll be able take the time between encounters to craft new items or enhance existing items for your troops, as well as to venture into a phantasmal plane, in which you can fight waves of genma for experience points (and a special bonus if you can get all the way through these levels). Most RPGs or strategy RPGs let you buy and sell equipment by visiting various shops around the world. There are no shops in Onimusha Tactics, but the item crafting system is functionally identical. Basically, as you defeat genma in battle, you'll automatically acquire a variety of different "genma stones." These may then be transmuted into different items--provided you've found the proper "recipe." Recipes are randomly found when a genma is defeated, and later they can also be stolen from certain foes. A recipe will allow you to make new weapons, armor, accessories, or items using a certain number of your stones.
Additionally, weapons and armor may be enhanced using a system similar to that of the previous Onimusha games. Whenever Onimaru or one of his allies kills a genma, its soul is absorbed by his gauntlet--these souls, in turn, are a sort of currency for item enhancement. Each weapon or suit of armor may be upgraded four times, and every subsequent step costs more souls. In practice, you won't be able to upgrade all your weapons or armor, and you'll find that weapon upgrades give you more value for your genma souls, so you'll probably conserve your resources for those. Also of note, like in other Onimusha games, the way in which you defeat your foes influences how many souls you get. If you're fortunate to kill a genma with a critical hit, you'll get a bunch more souls than usual. Most characters in Onimusha Tactics can also use the "issen" technique, a defensive countermove that randomly becomes available, allowing the character to instantly slay a foe attempting to directly attack that character in the next round. Issen moves, in addition to being cool-looking instant-kill moves, also net you a ton of souls.
The fact that the issen technique becomes available randomly is evidence to the relative lack of depth in Onimusha Tactics. Strategy RPGs should be all about careful planning and the careful balance of risk versus reward. However, Onimusha Tactics doesn't really reward you for going out of your way to plan complex strategies. For example, unlike other, similar games, Onimusha Tactics doesn't seem to give you an advantage for attacking foes from the flank or from behind. Also, though your characters will earn a few different special techniques as they gain experience levels, they'll largely depend on one type of weapon to do all their damage. So, for instance, sword-wielding characters can upgrade to better swords, but that's it. Some genma obviously present different types of challenges than others--some may attack with powerful ranged spells, while others may explode when defeated, damaging all adjacent units. But there still isn't much variety to these battles, except for a few more-scripted battles that will throw a few surprises your way.