Northmark is a pretty nice, though very short, single player CCG.
The actual combat mechanics are different from other CCGs I've played. There are 4 types of cards - Units(soldiers, etc), Buffs, Debuffs, and Attacks. Before the fight starts, you select up to 3 unit cards and 12 of the other cards from you inventory for your deck. The units start out right on the battlefield - no need to "summon" them, and your "Hand" contains 7 cards randomly selected from your 12 card deck. As each card is used, it is replaced by another one, and the deck never "runs out." If your deck contains fewer than 12 cards, the remainder are a random assortment of very weak cards.
Units have two attributes - Health and Defense. Defense is subdivided by element - Physical, Magic, Fire, etc. Every unit in play gets a turn - if you have 1 unit and the enemy has 3, they take 3 turns for every one of yours. Every unit has at least a couple of cards of its own. When the unit takes its turn, you can have it use either one of its own cards or one of the 7 cards in your hand. Its own cards aren't "rotated', but instead put on a cooldown for several turns after use. Every action uses a card, for example an Attack card needs to be available in order for the unit to attack.
The goal is to eliminate the enemy's units. Damage calculation is simple - if your Wolf uses its Wolf Attack card, which does 4 physical damage, against an enemy's Soldier who has 1 physical defense, the result is 3 Hit Points subtracted from the Soldier's health. Your unit actually gets attack and defense bonuses from your hero's stats, which you increase when you level up, and the enemy has their own bonuses, so if the enemy hero has +3 to defense and you don't have any attack bonuses, the Wolf will not do any damage. That's where buffs and debuffs can come in - I often found it a useful strategy to have 2 units use their turns to buff up the attack strength of a 3rd unit, which would then rip through any enemy defenses.
There are no resources like mana or energy in combat - if you have a card in hand, no matter how powerful, any of your units can use it on their turn, so it pays to try to get the most powerful cards you can. This doesn't quite apply to the units themselves. Your hero has a "leadership" attribute (which increases either as you level up or as you proceed in the plot, I'm not quite sure,) and each unit has a set level of 1 to 5. The combine levels of the 3 units fielded in battle cannot be greater than your leadership value, so if you want to use 3 level 5 units, you need leadership to be 15.
When you begin a new game, your character will start out with 3 cards specific to your chosen class, including 1 Unit card and 2 cards for your battle deck. Some of the other cards you will find after combat, in hidden stashes, or be given as part of the plot or reward for completing a quest. Most cards, however, you will purchase from shops with gold (which is found after combat, in hidden stashes, or given to you as part of the plot or reward for completing a quest.) Various of the cities you visit have arenas in which you can fight, with no penalty for losing, until you defeat each of the opponents. The gold rewards for wins are very nice, not to mention the XP gained, so it is highly recommended to do these whenever possible.
The graphics are serviceable, and the music is very good though there isn't a large variety of tunes. Interface is decent, with the strange exception of when it comes to modify up deck - clicking on one of the twelve slots let's you select replacements, but you can only see 3 cards at a time, and have to click the arrows to scroll the 3-card view in any direction, 1 card at a time. Obviously this can be quite maddening, as your card inventory grows. You can view your inventory at and see 18 cards to a page, so it makes no sense why a similar large page view can't be used to select the cards for teh battle deck...
As I stated in the beginning, this game is rather short, too short in my opinion for the $9.99 asking price. It can be completed in 4 hours, and there's not very much replay value besides seeing how it plays with a different character build (ex. putting all your level up points into Ice Attack and seeing what happens). While you do get to pick a character and class when starting the story game, these have no effect beyond the couple pre-allocated skill/level points and the 3 cards you start the game with. And the final boss feels more like a "Saruman" than "Sauron", leaving the the whole story feeling more like a "Part 1".
There is also a Quick Battle option in the main menu, where you can select a character and level for yourself and the AI, from 13 different types of characters which you might face in the story campaign. Each of these has their own cards and units, and this is your chance to use some cards which you've only had used against you in the story.
In the end, due to its short length and lack of multiplayer, I'd recommend this game on a sale. If you can get it for <$3-4, it's a good value. For a more "meatier" single player experience, you'd want to look at other titles, like Spectromancer .