Something like the Zero Escape series (can't remember if credits even roll for the bad endings), just getting an ending without going through the various routes isn't sufficient. Having multiple endings is actually part of the plot of those games and, while you might not need to go through every single route, you really do have to follow the arc to its real conclusion to finish the game, so there is an example where just getting to an ending is not sufficient. I suppose you could make an argument that "bad" endings never count as completing the game, but I won't, especially given how nebulous the term "bad" ending is. Losing to Lavos definitely does not count as completing Chrono Trigger, but in a game where you can finish the gameplay aspects and still get a "bad" ending because you failed to tick off some boxes? I'm still counting that as finishing the game. Suikoden games are finished regardless of whether you got the 108 stars and saved whoever for example, so long as you beat the final boss, and got to the part where they show the fates of all the characters you've collected. I'd never be satisfied that I've done what I wanted with the game without getting all 108 stars and the best ending, but I still think that it's completing the game (and I usually do a run where I just get all the stars I manage to on my own and then a run where I make sure to get all 108 - except Suikoden IV where I made bloody sure to get all 108 the first time because I knew I was never playing that POS again).