Knights of the Chalice ($24, free demo) is a cheerfully old-school game in which blocky, two-dimensional characters wander a blocky, two-dimensional world in order to gut and eviscerate everything that moves and haul off as treasure everything that isn't nailed down. In some contexts, this would be the work of sociopathic brigands; in the world of role playing games, it's called "adventuring."

Instead of a limited subset of the main game, you get a small, standalone adventure, with pre-generated characters. If you like the gameplay and purchase the full Knights Of The Chalice game, you get a much larger game (going to level 20 instead of 3) and you can create your own band of intrepid heroes. This unusual demo model gives enough of a taste of the gameplay, tactics, and interface that you'll quickly know if you'll enjoy the full game.

Knights Of The Chalice uses a highly modified and simplified form of the Dungeons & Dragons 3.5 rules, thanks to the Open Game License. There are only 3 classes (Fighter, Wizard, Cleric), no skills, and only a handful of feats. What is carried over is the importance of tactical positioning. Flanking an enemy is important, moving past a foe will let him get a whack at you, and casting a spell next to an enemy--or in the sight of an enemy with a bow--is dangerous. (Eberron Online is a more robust implementation of the D&D rules set, but it is oriented towards the real-time play of an MMORPG, as well as having the traditional D&D levels broken up to allow more frequent rewards and advances.)

Let me expand--being a spellcaster is dangerous. Every fight I experienced in the full game followed this pattern:

a) My adventuring party gets a screen message alerting us to monsters in the area. The monsters then spawn all around us.

b) The monsters all get to attack us before we can act. There's no way our initiative rolls can be that bad that consistently.

c) Because we can't position ourselves until after the monsters have swarmed in from all directions, they focus fire on my wizard and knock her out in the first round. Every. Single. Fight.

I am all for challenging and complicated fights, but many of the battles in Knights Of The Chalice seem overly stacked against the players, especially the unavoidable ambushes. It's one thing to stupidly wander into an obviously high-level area, it's another to be told to go to a place as part of your starting quest and be jumped by enemies much more powerful than you with no chance to retreat or get into a decent fighting formation. Sometimes, though, this is a warning--advice I received was that if you're dying a lot in an area, even one you've been pointed at by quests, you should go back to lower level areas and just kill things for a while.

The toughness is no accident; in a conversation with the game's creator, I mentioned an unexpected attack I experienced going back through an 'explored' area after killing a major enemy; his reply was " Ahah, yeah, I like that little surprise." So, be prepared to be challenged more than in many games, but skill, patience, and a little luck will get you through.

The interface of Knights of the Chalice is entirely mouse-driven, and it is a bit odd, though not impossible to get used to. Many actions which would be select and click in other games are click-and-drag in this; for example, to sell a sword, you drag it from your inventory to the "Sell" button on the merchant.

A tactical hint: Take the crafting feats! A wizard with a backpack full of scrolls is much more useful than a wizard without one, and I suspect the fight balance is set on the assumption you'll be loaded with scrolls and wands. Another important hint is to check the Constitution of your party members before you begin adventuring. A low Constitution score can produce cripplingly low hit points, and you cannot replace an individual character once you've begun--instead, you must begin with a new party.

Knights Of The Chalice promises a tactically deep combat system and enough of a storyline to keep you mildly amused as you explore caverns and towns, looking for things to kill. If 2-D, 8-bit style, graphics and turn-based gameplay aren't deal killers for you, it's absolutely worth trying the demo--and if you like it, the full game has a lot more of the same style of play.