The debut set of Stargate TCG drew on images, characters, and plots from all throughout the 10 seasons of Stargate SG-1, and over two-thirds of the episodes were represented on at least one card. I'm sometimes asked: are cards inspired by watching the show, or are things from the show found to fit the cards after they're written? The answer is, we do plenty of both.
A "story driven" card design can begin for any number of reasons. Fans of Stargate are quite vocal about which episodes are their favorites, and some cards were created specifically to feature images from those episodes. The fans are equally vocal about which characters are their favorites (especially recurring characters), so some cards simply begin with the mandate "we have to capture this person on a card." One specific card that had a story-driven genesis was Joe Spencer:

Of course, the episode "Citizen Joe" doesn't rate high on most fans' favorites, nor are there loads of people wishing the character had appeared in more than just that one episode. He's an example of the most common reason a story driven card is created -- he's part of a very evocative and distinct storyline in the show. An ordinary outsider who shares a telepathic link with a member of SG-1? The concept almost demands representation in the game, and immediately conjures several ideas for how to do it. (Not just the version we ended up making.)
There was one other factor, that while not as commonplace or important as a purely plot driven inspiration, certainly helped Joe Spencer make the cut over the thousands of other characters we could have chosen -- he was played by actor Dan Castellaneta. Not everyone will recognize his face, but he's the voice behind Homer Simpson, beloved by many including the character of Jack O'Neill and the actor who plays him, Richard Dean Anderson. Even if Joe Spencer hadn't been part of a story that inspired instant creativity, he probably would have been high on our "to do" list anyway. And that again would have been a story driven design, as we then would have taken his character's story -- whatever it was -- as a jumping off point for creating a card. It's not often that a character makes it into a set only because of the actor playing him, but it does happen.
On the other end of the spectrum are cards that start out purely as a piece of game text, which later are matched up to something from the television show. In this case, having so many hours of material to draw on is a real luxury. You can find something, somewhere in some episode, that feels like a natural fit for almost any bit of gameplay you can dream up. One example of such a card is Martin Lloyd:

When we were first testing the prototype design for Stargate TCG, it didn't take us long to notice that the villain player often behaves in a particular way: he usually sits back and waits to play any cards until after his opponent has assigned enough skill to succeed. That's a logical strategy, and we didn't mind that that's how most players would play the game. But at the same time, we thought it would be interesting to create a few cards that threw a wrench into that typical way of playing.
But he wasn't called Martin Lloyd at first. He was just "Pumpable Ingenuity Guy." With my "designer hat" on, I was really excited by the way this card would change the normal pattern of attempting a mission. But looking over at the rack where my "story hat" was hanging, I worried that I'd have a really hard time later on, when I had to be the person to find a character from the show that this matched. How could it make sense for a character to keep getting "smarter" just because the bad guys were sitting around doing nothing?
I really shouldn't have worried. Days down the road, when I did put the "story hat" on, I realized this was actually a really easy situation to explain for any skill. An archaeologist at a dig or scientist perfecting a new invention would certainly have more time to learn something valuable without an enemy beating down the door. A tactician would be able to create a better plan to defeat an enemy, the more time he's given to work on it. That would cover Culture, Science, and Combat quite nicely, should we ever want to do those cards. As for Ingenuity? The Martin Lloyd story seemed tailor-made for this gameplay. In the show, the longer he went without being forced by the bad guys to take his memory-suppressing medication, the more he'd remember about his true alien identity.
Both Joe Spencer and Martin Lloyd are fairly popular cards with players. I think this shows that it doesn't matter whether story comes before gameplay or gameplay before story -- both methods can lead to an interesting and useful card. When both those elements come together well, players shouldn't even be able to tell which piece actually came first. It should just feel natural when a fan of the show looks at a card: "of course this card would do that."