It really sounds like, then, that the Google Docs could be useful for several of the points in the list:
1) Use an experience system 2) Multiple long and short term aims 3) Reward for effort 4) Rapid frequent clear feedback 5) Element of uncertainty 6) Window of enhanced attention 7) Other people
It looks especially like Google Docs (Drive, whatever they're calling it this month) works for rapid frequent clear feedback. I like your idea, Mina, about using a quiz to get students further in your IF.
I've read about systems that have those kinds of mechanics built in (Edmodo for example), but I'm always leery about introducing too many different regular websites for students to use.
I share this reticence. I've switched to using all Google apps because, as you point out, they really do allow you to address all 7 reward principles. I have all students create a Google account (many of them already have one) and that allows them to use all apps for the class (Google+ for communication, Blogger for blogs, Sites for websites and wikis, etc.) with a single username and password. And since all Google apps are linked, it reduces leg work for the students (their blog posts automatically get published to Google+ for example).
I'm using the AXMA program (which is a version of Twine) to write the IF and it allows hyperlinking to outside sites and it may even allow embedding HTML (haven't gotten that far into writing the game yet), so since Forms provides an embed code, I may be able to just embed the quiz directly into the game.
1) Uses an experience system No experience points. Experience provides insights to improving scores, though.
2) Multiple long and short term aims Short term aim is spell a word fromt the letters displayed. Letters enter the screen from the right and if not played in time, exit off the left. There are a set number of letters available. Long term aim is get as many points as possible and maintain a high average.
3) Reward for effort Higher points are rewarded for good effort, i.e., finding words to spell. Spelling unusual words yields a higher score.
4) Rapid frequent clear feedback Sound effects mark different milestones in the game. If you misspell a word you are not awarded any points.
5) Element of uncertainty The element of uncertainty is whether your brain is going to make associations quickly to form words.
6) Window of enhanced attention No big surprises but when you come up with a great word you immediately hunker down and try to beat it.
7) Other people The game compares your scores with others playing the game and gives you a ranking. There is no direct competition with others.