Thanks for the review!
It's not too likely that Happy Birthday will get any extra endings or major changes at this point (though I do plan on putting up a minor update with some bug-fixes and edited text soon), but I would definitely like to make a less rushed, more fully-fledged sequel with a lot more possible routes and endings included. I'll keep the rest of the feedback in mind for the future, too (I do need to work on making better use of SEs - they were pretty neglected - and CGs would be awesome).
Anyway, glad you liked it for the most part.