The premise of Shining Force II is simple and familiar: a kingdom is facing peril due to a silly, seemingly small mistake. A character named Slade, a common criminal, is attempting to thieve from a shrine and, while doing so, breaks a magic seal and releases a demonic king. NBD, right? Wrong.
The king is undertaken with a sudden illness and a group of merry men go out into the wilderness to see what has happened. Upon this embarkation into the woods, the men discover that not only is their sacred Tower of the Ancients unlocked, but it has also been taken over by Gizmos—a form of devil or demon. Based on this, the Shining Force is born as is the plot of the game—the men need to find the Holy Sword to banish this demon, exorcise the demon from the king, and regain control of the two jewels of Light and Darkness that that jerk Slade stole in the beginning of the game.
The mechanics of the game are basically the same as other canonical RPGs. The graphics look similar to many other games of the time, overhead view except for when in battle. The character that you gain control of is Bowie, the charismatic leader of the Shining Force. By accomplishing goals and moving through the plot of the game you can subsequently pick up new party members—each with a unique class that then adds additional capabilities to your party.
Similarly, you are able to level up by gaining experience points in the expected ways: killing enemies in turn-based battles, completing tasks, and so on. Once reaching level 20, you are able to select to a more powerful class, similar to transcendent classes in Ragnarok Online, if you have ever played. That, I think, is one of the more unique traits of this Shining Force II.
While this does sound pretty basic, and the plot is now quite a common one, at the time of its release in 1993, this game was pretty forward thinking. If you haven't played it but are interested, you can play it here as a emulation. It was also released for Steam in 2008. Let me know what you think in the comments!