Re: Is this game going too big in proportion too fast?
(Some players might not get this little joke if you don't know the commercials!)
Joking aside, we don't know how Haypi is planning to progress in this game.
Firstly, the rank (rarity) of the monsters doesn't necessarily suggests how far along the game is to a decrease of its updates. There are way too many features that may be added in the game - not just more monsters all the time.
Haypi might already have a plan on how to upgrade the game.
I used to play a game (a couple of years ago) which had a similar progress record as this game but they are still going strong today and a lot has changed.
Definitely more monsters will be introduced and the popular franchise this game seems to be modelled from is going strong with more than 1000 (as far as I know) monsters.
Just because legendary monsters have been introduced does not at all imply that this game is nearing its end. In the feedback contests, there are still a lot of features that were suggested but weren't implemented yet. I am sure that Haypi has a lot more in mind as well.
Don't worry too much as it's only been half a year since the game came out. There are so many possibilities with this that it is highly, highly unlikely that it will come to an end any time soon.
Have fun for now! Enjoy it for now and don't think about the future way too much - with regards to the game anyway. Remember that you're playing this game as a hobby, more likely to escape real life and be submerged in a whole new world - or just chat with other players. There's no need to plan your Haypi career yet!
As my signature says:
"The past is history, the future is a mystery and today is a gift!"
and today is a gift."

Haypi Monster S11: Lexoph