Well, just to whet your appetite (and I WILL be rambling here), there is strategy involved, and the digital "cards" are both collectible and tradeable. The game has a detailed backstory that players learn about in minute tidbits through each card's flavor text, and in broader strokes by using those cards in game play and getting caught up in the storyline. There will be two play modes: (a) single player versus the game; this will be a longterm campaign that will be experienced as each succeeding expansion of the game is released; (b) turn-based multi-player versus game which will be transacted by each player submitting their turn's actions to their group's coordinator (the player on a team who collects each team mate's moves, adds her own, and then has the game engine process them).
The theme: I really must be intentionally vague here, in order not to give away too much too soon. The setting lies in a future time in which mankind has been and continues to be at risk of extinction caused by outside influences. Technology has advanced to a point, and the incursion of alien infuence has impinged to such as degree, that tropes from science-fiction, fantasy and other subgenres will be noted, but in such as mixture as makes sense against the unfolding backstory.
Each new "chapter" of the game will come in the form of an expansion that will either be a large binary download or may optionally take the form of separately titled executables.
The cards: the digital, collectible cards — beyond the starting cards each player gets — are unlocked through either victories (in the multiplayer turn-based mode) or achieving story goals (in the single-player mode). They aren't purchasable. But they are tradeable among players who have ever been grouped together into a team (in any phase of the multi-player mode).
Grinders who want to go it alone WILL be able to unlock new cards as storyline achievements. Multi-group players will each export their turn-based actions and send an encrypted data blob to their group's coordinator (whether that be via email attachment, file sharing service, download, etc; I don't envision this as a server-based game, but who knows). For the last few months I've been writing and rewriting segments of the backstory. It is designed so that the overall "big picture" takes lengthy game play to resolve. Even then, different players may have different interpretations. The game will, however, reward those whose interpretations align with the game designer's intent.
If the game were to become hugely popular, I've not ruled out some small fee ($0.99-2.99) per expansion, but players will NEVER be able to purchase/sell cards. Rarer cards will, naturally, require lengthier game play to obtain. Not only are the cards categorizable by their relative rarity. They also will have a GUID attached. Your "Big Bad Card" will not have the same digital fingerprint as mine of the same name. Not only that, but at milestones in the story mode, or after particularly boss-level victories in multi-player, there will be the chance of obtaining one or more unique cards (only one such card in existence, regardless of how many copies of the game are being played).
I would love to have beautiful artwork for the cards, but can't afford it. Maybe some zealous individual with talent will become interested in co-development. A trend in digital CCG's is lack of artwork; in several recent digital CCGs a simple array of icons is used. But I think artwork evoking the backstory would be super cool. Another thing about the cards. Unlike in, say, Magic: The Gathering, where Fireball is the same, no matter whose deck it's in, in this game some cards will be upgradeable via either prolonged use and familiarity or by discovering some factoid via the game that unlocks the next level of the card's potential.
This won't be a video game. No Unity 3D. I will develop it with the tool I'm most comfortable using: Visual Studio, using C#.