I am designing the game to be playable with a group but also for solo play. With solo play, I figured you could use it to generate a random language, or you could put up the cards that would mostly describe your own conlang, and then be able to play around with the language by substituting, adding, or taking away some of the cards. Also, you could more easily understand other conlangs by putting up the cards that create that conlang. After doing this a few times, you would sense patterns between the cards for how certain languages sound and behave. If you an amateur linguist (like me), developing a recognition for these patterns could be really helpful to wrapping your head around and learning linguistic principles.
In addition to all this, after I'm done making all the cards, I want to make a flash game which you can play, and make it even easier to play with language, being able to click and drag cards around and such. Also, I want to make it so that you can develop a conlang in the game, and have it spit out a long code which you can copy and paste. Then you could post about your language online, include the code, and others would be able to paste the code into their flash game and see your conlang pop up on the screen! I think could work much more quickly than having to write out your entire phonology, morphology, syntax, grammer, etc. Especially if the code is in a file that can include a lexicon and notes on the language. It could make Conlang Relays a smoother process and more fun! But thats probably a couple years away still.
Please comment if you have any helpful ideas or if you think this can't be done. I'm interested to hear your opinion either way!