Just some advice for devs as its a common pitfall I see...
Try not to release the game with too little content, or having progression stop just before, or just as its about to get good.
Personally, I've played a boat load of these games and I almost never return to any of them. Even years later...
I won't want to sink the 2-3 hours to get back to where I was, and I won't want to pick up with just the new content as I have no idea what's going on... So there is a good chance that the best content your game receives will not be seen by the greatest audience.
You will be better off releasing a game that is designed to be a condensed 2 hour experience, than release the first 2 hours of a 10 hour game that people wont return for.