I know this game and others of its ilk are out there, but for the life of me I can't ferret it out.
My 12-year-old has requested a card-driven game (draw from a personal deck, small 4- or 5-card hand) where you explore a map board (discovering new terrain, maybe? he didn't say). The cards give you powers or special abilities, or dictate what features appear on the map. Non-historical theme, so I guess wargames are out, but he's leaning toward something with direct conflict; a fantasy or sci-fi theme is okay/preferable. He also expressed a preference for miniatures, so something Ameritrashy seems reasonable.
The best I could get out of him when asking for examples was this scene from Adventure Time, where they're playing Card Wars:
(Despite that clip, I don't think that Adventure Time Card Wars is what he's looking for, since it's missing the board and minis -- he seemed pretty adamant about the board and minis -- although I may be wrong.)
So, to recap:
* Hand management * Board/map w/ exploration * Direct conflict/combat * Sci-fi/fantasy theme * Minis
Any help? I throw myself at the mercy and the collective knowledge of the Hive Mind! Many thanks in advance!
Mage Knight Board Game - hand management - cards (deckbuilding) are the main mechanic, you perform all your actions with the cards you have each turn, you move with them, you fight with them, you heal, recruit, etc. - board exploration - very much so, you start out with only a small area and have to explore the rest of the map - combat - it is fully deterministic, however, might not be as exciting for him - fantasy - check - minis - only one per hero and one per city (main goal is to defeat those), all the monsters you are fighting are cardboard chips
... or maybe ...
Runewars - hand management - to a degree, you have a number of strategy cards and pick an order in which you use them, but not nearly as much as Mage Knight, where the cards are the driving force behind the whole game - board exploration - there isn't a whole lot of that, the map is fully visible from the start; it is more expanding than exploring; it does offer a little of that with the heroes - combat - it does have very direct conflict and interesting combat - fantasy - check - minis - definitely
The first two are tactical warfare games that use the Commands and Colors system. One has a fantasy setting and the other has a sci-fi setting with mechs. Here's some information from the BGG page about the system, in case you're not already familiar with it:
Common elements of all Command and Colors games are a deck of Command Cards, which can be classified as Section cards and Tactics cards, and Battle Dice. In the Command and Colors System the playing field is divided into a center section and a right and left flank. Section cards are used to allow the ordering of unit(s) occupying one or more sections. Tactics cards are also available to allow special attacks. Another identifying feature of the system is the use of battle dice to resolve individual battles.
The last one is based on an earlier game called HeroScape (which you may already be familiar with), where a player controls one main hero, called a planeswalker (basically a mage), who can summon various creatures and use them to attack his opponents planeswalker and creatures. Each player gets a deck of cards that represent various spells and abilities that they can use in their efforts to defeat their opponent.
One more that popped into my mind as I was writing this is Clash of Cultures. But I honestly don't think I would recommend as something that fits your criteria. It's a pretty heavy game for a 12 year old, and I don't think the way the cards are used in that game is what he's looking for. It does however offer exploration of terra incognita and lots of miniatures. It's a civ-building game where each player builds up their own civilization (bronze-age) and gets to expand their territory into previously unexplored parts of the map, while building a tech-tree and managing conflict with the other players. Cool game, but probably not what you're looking for.
EDIT the above mentioned Mage knight is perfect but may be too meaty a game for his age range. But do not let that put him off as enthusiastic kids will persevere to learn a good game.
FWIW, my kids (boys 10-12 yrs old) really like Mage Knight. We always play it co-op. The They love the levelling-up aspect and fighting monsters. With no player-v-player combat, the game doesn't end in tears from someone or other. It is a very long game though. Best to have somewhere you can leave it set up while playing over a weekend.