It's not about "good" or "bad" or "heroic". It's about "satisfying". All in all, the player should feel happy that he played the game to its completion.
Exhibit A:
Sonic '06 (the epitome of what not to do with big-league game design) technically had a "good"/"heroic" ending, but it was unsatisfactory (to many) because it
retconned itself out of the series' storyline. That's right, surviving the stupid programming bugs, crappy level design, and overall
badness of the game is all for naught in the end. Ouch. Then again, the game's insane, inane plot makes no sense to begin with, so it fits...kind of.
- Point A: An ending should make as much sense as its plot. Gainax Endings are not for everyone. The last thing you want the player to say after playing the game is "BS!"
Example B: In Peter Jackson's adaptation of
The Fellowship of the Ring; the movie just ends after one of Gimli's lines. Gimli just says "I hope they're all right" or something (I've forgotten most of the movie) and CUT! We're done here. Abrupt cliffhangers can kill immersion. That said,
The Fellowship of the Ring is excusable because A: an adaptation of
The Two Towers was practically guaranteed and B: segueing right into
The Two Towers and
Return of the King would make for an impossibly long movie.
- Point B: But for an RPGMaker game, sequels are not a guarantee, so ending on a cliffhanger that may never be resolved is a proverbial kick in the proverbial balls. It's better to wrap up the loose ends in-game than force the players to wait for an entirely new game.
Example C: As for "bad" or "sad" endings in video games, look no further than
Spec Ops: The Line, one of the few games that berates the player for playing it. Even the lead writer had a nervous breakdown. The game wants you to feel like $#!+ for playing it, and for playing brutal shooters in general. And it does this with all the subtlety of a tank rolling through Tienanmen Square. The only winning move is not to play. Deconstructing the realistic shooter genre is the game's point.
- Point C: Odds are, your game is not intended to be a savage deconstruction of the RPG genre. If so, congrats, I guess. But unless the players are well-attuned to the idea that their actions will only make things worse, they will likely end up disillusioned, or in Spec Ops' case, insulted. Of course, since your game isn't intended for mass release, you can also make things more grimdark than Spec Ops. Just don't expect it to sell well...