ME3 seems to be the elephant in the room, but haven't played it. I guess I could nominate the following:
-Golden Sun: Dark Dawn (in that it ends with a cliffhanger that's yet to be followed up, and may never be, not to mention that The Lost Age conspicuously didn't resort to such a tactic)
-The Lord of the Rings: The Third Age (in that we skip right from the Pelannor to fighting Sauron's eye for some reason, and then end with a monologue from Gandalf. Not too bad, but it's telling how none of it factors into the actions of the characters, since it's re-using movie footage)
-Super Metroid (in that Zebes is destroyed, the infant is gone, Mother Brain is finally defeated, and...there's nothing to mark the event. Roll credits. Don't let the door hit you on the way out)
-Resident Evil Gaiden (in that we have yet another cliffhanger that's never followed up - granted, the game's absolute garbage anyway, so who cares, right?)
-Sonic Chronicles: The Dark Brotherhood (and yet another unresolved cliffhanger...gee, are you starting to see a pattern here?)
-Golden Sun: Dark Dawn (in that it ends with a cliffhanger that's yet to be followed up, and may never be, not to mention that The Lost Age conspicuously didn't resort to such a tactic)
-The Lord of the Rings: The Third Age (in that we skip right from the Pelannor to fighting Sauron's eye for some reason, and then end with a monologue from Gandalf. Not too bad, but it's telling how none of it factors into the actions of the characters, since it's re-using movie footage)
-Super Metroid (in that Zebes is destroyed, the infant is gone, Mother Brain is finally defeated, and...there's nothing to mark the event. Roll credits. Don't let the door hit you on the way out)
-Resident Evil Gaiden (in that we have yet another cliffhanger that's never followed up - granted, the game's absolute garbage anyway, so who cares, right?)
-Sonic Chronicles: The Dark Brotherhood (and yet another unresolved cliffhanger...gee, are you starting to see a pattern here?)