dunno man, 4 elements trainer pretty much just finished, and went on a high note. it did have its dev problems, but overall? it was a smooth sailing, with each "book" having its fans, and majority of players happy with the results.Seems all the long running games turn to shit eventually, this game now, Ecchi sensei with its 2 years of weak ass excuses as to why there is no update, the tyrant and so on.
All those devs got the support they wanted at first but when they saw the easy money they scaled down the updates and made them less frequent to have the keep the moneymilking machine going for as long as possible
as for something unlimited, for as much milking the guy does, the game has the content to back it up. so its a toss up there.
same can be said with rogue like, which, i do think its gone downhill, but again at least the devs didnt take time to make the game worse, so there's that.
glassix, harem hotel, come home and many other smaller, but long dev projects may not be as big, but dont seem to have gone bad either.
of course, we just lost another big one with venture seas(but lets be honest that game was fated to fail from the start with how borked it was).