Importance of theme in a cooperative game

Future Wolfie of iSlayTheDragon recently reviewed Samurai Spirit (designer Antoine Bauza, artist Victor P. Corbella, publisher FunForge).  It seems like an interesting game - I've got it on my wishlist - but a couple of sentences in Future Wolfie's review jumped out at me:

In a way it’s like a cooperative version of Blackjack, with much better art and a few special powers thrown in the mix. But that’s what it really boils down to in a sense: trying to hit a maximum total card value without going over.

In that brief characterization, the concept of the game as a Blackjack variant completely undermined the premise of the game as a representation of fellow Samurais defending a village from invaders.  From that point forward, Samurai Spirit was a card game with art, rather than an adventure conflict using cards as a participation medium.  The theme became secondary.  Moreover, as a co-operative exercise, its appeal as a game diminished drastically for me.

This perspective illustrated to me that an easily abstracted (i.e. weakly themed) co-op game loses its appeal.  The corollary follows that strong theme is more important to motivate co-op gameplay than it is to motivate competitive gameplay.

A few examples and counterexamples might help to explore this thesis.  Some of the most successful co-operative games thrive on their themes.   

• Pandemic (designer Matt Leacock, artists Josh Cappel and Régis Moulun, publisher Z-Man Games) is arguably the most successful co-op game and richly conveys the thematic stress of spreading disease and a race against the clock to find cures and contain the epidemic.  
• By all accounts, Flashpoint: Fire Rescue (designer Kevin Lanzing, artists Luis Francisco and George Patsouras, publisher Indie Boards and Cards) engages players immediately and deeply in the theme of a firefighting setting, with emotional investment in rescuing the victims.
• Dead of Winter (designers Jonathan Gilmour and Isaac Vegas; artists David Richards, Fernanda Suarez, and Peter Wocken; publisher Plaid Hat) is perhaps the most acclaimed and sought-after game of 2014 - again, rich in theme, which drives the excitement of the game.
• Mice and Mystics (designer Jerry Hawthorne, artists John Ariosa and David Richards, publisher Plaid Hat) thrives on the stories it tells.
• Keith F. reminded me of the currently Kickstarting Salvation Road (designers Peter Gousis and Michael D. Kelley, artist Venessa Kelley, publisher Van Ryder Games), which I saw (but didn't play) at UnPub 5 and which has all the hallmarks of a highly thematic post-apocalyptic survival game.  This one got consistently exciting buzz from those who played it at UnPub.
• Castle Panic (designer and artist Justin De Witt, publisher Fireside Games) was the first co-op that my family played, based on a recommendation from my son who had played it with a friend and came home raving about it.  CP still a family favorite for the excitement and tension that come from watching the walls get knocked down as we desperately fight off the last of the advancing hordes.

Besides Samurai Spirit, a couple of other interesting counterexamples illustrate the premise that weakly themed co-op games don't hold up:

• Hanabi (designer Antoine Bauza; artists Antoine Bauza, Gérald Guerlais, and Albertine Ralenti; publisher R&R Games) has proven to be a fairly popular cooperative game that is to all intents and purposes an abstract card game.  Notably, Antoine Bauza designed both Hanabi and Samurai Spirit.  I've played Hanabi, and although it's an enjoyable little game, it's doesn't deliver nearly the excitement that every thematic example listed above does.
• Brian "StormKnight" Modrecki and Lisa "Nightmare" Bjornseth posted a Crazy Couple review of Dungeons & Dragons: Castle Ravenloft (Wizards of the Coast), which appears to be another example of a disappointing co-op with weak theme execution:  

The illusion of anything interesting going on dropped off very fast. Draw a card, see how many hit points you lose. Roll to hit. Draw a card, see how many hit points you lose. Roll to hit. Over and over.

So, if strong theme is so important to enjoyment of a co-op game, why are abstract competitive games still successful and engaging?  I'd hypothesize that competitive games derive their excitement from the challenge of the competition itself.  An abstract game provides a ruleset and framework for that competition; theme is secondary to the gameplay.  A co-op, on the other hand, poses the players against a game system rather than against each other.  It may be that puzzle-solving in a co-op format doesn't offer compelling competitive engagement, so a strong theme is necessary for players to lose themselves in the fantasy of danger or a narrative story arc. 

This observation helps me prioritize the thematic basis for "Reactor Scram," the co-op that I'm currently working on.  Fortunately, early feedback at UnPub playtesting events suggests that players really do feel as though they are racing to prevent a nuclear disaster.  I want to make sure that I maintain that thematic linkage as I continue to polish the gameplay mechanics.