Even though I haven't heard this from a lot of gamers (Translation: This is probably more my opinion than a useful observation.), I think chrome and color are as important as mechanics in making a successful game. I think this is true for electronic games as well as board games. For example, there were tons of real-time strategy games (I contend this genre is mis-named and should actually be called "accelerated-time strategy games.") in the '90s, but only a few became phenomenal hits. Warcraft seemed, at first, like a generic fantasy game. But "Ready to work!" became a part of our universal gamer consciousness. Such touches added such slices of character to a universe unlike ours, but they sounded right. Imagine also how Sid Meier's Railroad Tycoon would have been without the evolving locomotives of railroading history. It just wouldn't have been the same without some continuity with locomotive designs. How would Age of Empires have fared without the different looks of its cultures?
Chrome in the world of board games can apply to something as simple as the tactile feel of a cardboard counter, token, action or playing card, wooden block, or miniature (or even something as visual as an elaborate poster of a technology tree or similar playing aid). The components and/or structure of a game are tremendously important for providing the kind of immersion that one quickly gets on-screen with an electronic game. Abstract games with cookie-cutter components and artwork are quickly relegated to closets and yard sales, but games that offer something different are games that can keep gamers like me hooked for years.
For example, the first time I played the wooden block game, Napoleon, I realized that I was playing something special. It was the first time I really understood the appeal of the Napoleonic Era. At the same time, it pointed me toward System 7 miniatures and other Napoleonic games because, for the first time, I began to understand some of the "cat and mouse" of maneuver that was important in bringing forces to bear in those famous pitched battles. The use of those wooden counters to provide "fog of war" or "friction" was a powerful metaphor for me. Though the same style of components work really well for different reasons in later games like East Front, Europe Engulfed, Hammer of the Scots, and Crusader Rex (and I particularly enjoy Europe Engulfed and Hammer of the Scots for entirely different reasons), Napoleon served as a conceptual blockbuster that widened my world of wargaming.
In a similar way, the process of "building a deck" for Magic: The Gathering was another conceptual blockbuster for me. On the one hand, the process seemed incredibly open-ended to me, and on the other hand, the process seemed intimidating. The game mechanics were accessible but challenging, yet the real appeal of the game was the ability to collect one's own art gallery of cards while customizing one's strategy. Other games had degrees of success using the collectible card game or trading card game format, but most of the games didn't take the time to commission paintings of the quality as those created for Magic. Some games, like Doomtown and Legend of the Five Rings came close to matching Magic's appeal with their storyline tournaments and licensed products such as the Star Wars and Lord of the Rings trading card games used their built-in audiences to approach Magic's success, but it wasn't until something with an entirely different feel, Pokemon came along that anything reached and surpassed Magic's level of success (even if only temporarily).
At the same time, Wizards of the Coast's own "ARC" series of licensed Xena, Hercules, and C-23 never managed to even compare with its marquee product. The mechanics were there, but the art and the feeling of customization just didn't compare. Aliens vs. Predator, Battletech Collectible Card Game, Blood Wars, Dredd (as in the infamous Judge), Dr. Who, Dune, and Harry Potter all missed the mark in terms of finding the right mix between art and gameplay. To me, none of them came close to capturing the feel of the concept or universe behind their titles like the ever-expanding Magic: The Gathering.
Arkham Horror was a huge surprise to me. I thought the whole Cthulhu mythos had become last century's news for purposes of gaming. Yet, the map, the characters one can play, the character cards, the counters, the monsters, and the game's objectives which change slightly from game to game provides an amazing atmospheric experience of the mythos that only misses the "fishy" smell. Whether the game ends in victory or defeat (for the group or individuals), this board game affords an incredible experience. As a gamer biased toward historical wargames, I was thrilled to discover this delightful game.
One simply wonders if Axis & Allies would have succeeded as well without its miniatures and it is clear that part of the appeal of the WizKids "Clix" games was the collectibility of the miniatures. I know people who simply had to have the superheroes, even if they never played the games. Of course, quality components are only part of the story. Eagle Games put out a formidable series of products with marvelous plastic miniatures and built off marvelous branding, yet the components drove up the pricing and the actual gameplay elements suffered from trying to get too many of the features of the computer game licenses into the games. As a result, their version of Sid Meier's Civilization suffered by virtue of being perceived as too lengthy and complicated while the more playable Sid Meier's Age of Mythology had some play balance issues that could have been addressed. Even with wonderful components, the games didn't perform as expected in the marketplace.
Of course, game designers don't necessarily identify "chrome" with the quality of the components. The components are only one portion of the look and feel of a game. Anything, even a random events chart or a minor rule (even an optional rule) that adds to the color of a game without destroying the game's balance (or unduly influencing the overall game mechanic) can be considered "chrome." For example, a rule in an early Vance von Borries design (I think it was Decision at Kasserine) had the possibility of Italian troops not having enough water to make pasta. This is not something one would ordinarily find in an order of battle, but it really offers a delightful bit of historical character to the game. More recently, Ed Beach's Here I Stand! has a delightful element where King Henry VIII keeps trying to get his heir. It was important with regard to Reformation Era politics and it is significant to this game. It may be "chrome" in that you can win without it, but it is definitely a terrific addition to the game.
As I said at the beginning of this post, I'm not sure all gamers will agree with me, but I think the color and chrome that designers add into the game makes all the difference in terms of whether I'll see this as just another game on the subject matter or see it as a fresh, new experience. Naturally, gamers want a mixture of comfort and surprise. If the experience is too new and fresh, it will be threatening and lack a great deal of fun. If it is fresh, as well as familiar (in terms of game mechanics and metaphors), it is likely to have considerable appeal.