I thought of a couple that were all the rage and then for some reason or another just kind of left. F-Zero springs to mind at first because I loved it on SNES and then kinda liked it in later episodes and then it was just gone.

Legacy of Kain was brilliant despite the very bad problems it had on PS1 where the hardware wasn't actually powerful enough to run all that was on the screen. Later 3-D game was one of my favorites ever and then they too, just kind of went away despite a brilliant story. I have heard that the developers continually butted heads and they kind of agreed to disagree and haven't done much since.

How about Twisted Metal?