A card/dice game by Thomas Denmark. It is not necessarily a CCG, though combining cards from the two decks released so far is possible.
The first release of the game, Tomb of the Lich Lord, was from Citizen Games; Denmark subsequently took Dungeoneer to Atlas Games for both the rerelease of ToLL under new rules and the new deck, Vault of the Fiends.
Essentially, Dungeoneer is all about the old-fashioned dungeon crawl, the oldest setting of roleplaying games. While the game presents no wonderful new developments in the genre, it's fun and well-presented. Adding to the mayhem is that the players, on their turns, get to play Dungeon Master against each other -- throwing monsters and deleterious spells at opponents.
Each set of cards is divided into four decks: Hero, Map, Quest, and Adventure.
Each player gets one card from the Hero deck; essentially, it's a character sheet. Character stats are Melee Attack, Magic Attack, and Movement. Hit points are always six, no matter if you picked up the dwarf warrior, the necromancer, or the scrawny halfling thief. Each character has limits of how many Treasures it can carry at one time, and how many Boons (beneficial effect cards) it can be affected with at once. While character cards don't have a place to note this, each character collects tallies of Glory and Peril by adventuring. Glory is spent on Boons and Treasure, sometimes on Quests; Peril is spent by other players to throw monsters or Banes at you.
Map cards define the dungeon; all except the entrance are played one per turn until the whole place has been explored. Room cards often have special conditions or traps. Doors may be open, locked (characters can bypass the lock by rolling 1d6, adding their Movement, and trying to beat its rating), or trapped (bypassed in the same manner as a lock). Corridor cards are generally the safest, though even some of these may be trapped. Each map card has Glory and Peril ratings, which are added to a character's total as he enters it.
Quest cards are just that -- quests. Generally, there's a problem of some sort (a fire drake in a certain room, a spirit who must be pacified), and a condition (defeat it in mortal combat is a popular one) which is usually random. Some quests are less standard; one from Tomb of the Lich Lord requires the player to fish from the Troll Bridge, rolling dice until the card is satisfied. There are also many FedEx quests -- pick up the lost mage/princess/evil artifact/whatever and escort it to a destination. Most of the quests raise the completing character a level; some give treasure as well. The object of the game is to complete three quests.
Adventure cards cover pretty much everything else. Encounter cards are monsters to be defeated. Players, during the Dungeonlord phase of their turns, get to play them against their foes. Boons and Banes are blessings and curses, ostensibly from the gods, actually from yourself or your fellow players. Boons, you play on yourself; they may grant you added damage against a specific monster or increase one stat. Banes do the opposite, and are played against other people. Treasure is, again, played on yourself; its effects are more varied than Boons.
Overall, Dungeoneer is lots of fun; the only real stumbling block is the confusing rules. As of the second edition, this is mostly fixed, though I still recommend reading them thoroughly before playing.