If you liked the pacing and mechanics of Gauntlet or the old Final Fight style of side-scrolling beat-'em-ups, then Mystic Heroes is a great expansion of and improvement on that sort of gameplay.
Sometimes localization teams have their work cut out for them. These people, whose job it is to take a game made in a foreign country and translate it, have to redo the text, the voice acting, and the manual at the very least. A good team works to convey the cultural nuances found in the game as well. So a game like Mystic Heroes, steeped in Chinese myth unfamiliar to Westerners, must be a real challenge. While the localization team for Mystic Heroes wasn't up to that challenge, the game itself stands well on its own. The end result is an action game with appealing and simple gameplay but with flat characters and no connective tissue.
Koei, the developer of Mystic Heroes, is well known for making games based on actual events from the Three Kingdoms period of Chinese history, with a few fantasy elements thrown in. Mystic Heroes, while nearly identical to Koei's Three Kingdoms-based Dynasty Warriors series in terms of gameplay, is pure fantasy. The action can be described as a mix between Gauntlet and a moderately complex fighting game: Like in Gauntlet, you take on the role of a single warrior fighting against a horde of enemies, but instead of just having an attack button and a magic button, you have a decent variety of close-combat moves in addition to both long-range and short-range spells, combos, and defensive moves. The way combat plays out does a good job of putting you in the shoes of an impossibly powerful martial artist, and you'll routinely be dispatching 10 or 20 enemies at a time. The moves are all motion-captured and blend into each other so well that when you get good at the game, you'll be able to pull off some really impressive-looking fights. If you liked the pacing and mechanics of Gauntlet or the old Final Fight style of side-scrolling beat-'em-ups, then Mystic Heroes is a great expansion of and improvement on that sort of gameplay, with lots of well-rendered characters onscreen.
With two single-player modes (story and survival) and a variety of both cooperative and competitive multiplayer modes, it might seem like the game has more variety than its progenitors. But each mode is more or less the same: you versus large numbers of enemies. The exception is the multiplayer versus match, in which you can turn enemies off. On top of that, not only are there just four playable characters who are somewhat differentiated by combat strength, magic power, and speed, but they also all fight pretty much the same, though two of them are somewhat more suited to close combat, and the other two are slightly more powerful spellcasters.
All four characters can use spells, though, and the spell system clearly shows that Mystic Heroes has a lot of breadth but not much depth. There are four element types for the spells and four different spell categories. A category will have two or three spells of each element type. While this sounds like a lot of spells, your character can use only one spell of each category in a battle. Spells can be used as part of a combo or when your mana meter is full for different effects, but having only four spells per battle can wear a little thin by the time you get to the end.
You pick the spells by choosing two runes before a fight. A rune will have up to four spells on it, one in each category. If both your runes have a spell in the same category, you must pick which one you want to use. While the game boasts more than 70 different runes, the spell abilities that any given rune grants are often also found on many other runes. Furthermore, many of the spells in the same category but of different elements have only minor cosmetic and effect differences--for example, bouncing blue ice crystals instead of arcing red fireballs. Your spell choice does require you to make minute changes in how you play, but the end result is that in single-player and co-op modes, spell use becomes a little repetitive. Against another player, you don't have enough options to be unpredictable. Still, what Mystic Heroes lacks in depth it makes up for with nonstop action. It's even justifiable, considering the bulk of combat is against very weak enemies who don't require a lot of fancy moves to defeat. Yet in a boss battle, or when playing against a friend or just for fun, a little real variety would have extended the playability of the game.