Remember those initial reviews of “Under the Dome,” most praising its considerable promise? And what about the gaudy ratings, giving CBS a rare summer hit? That all seems a lot longer than three seasons ago, much less the four weeks that actually transpired within the show’s universe. After running in increasingly preposterous circles (somewhat appropriately, given the shape of its otherworldly enclosure), the Dome came down, along with the curtain, in what turned out to be the series finale. Although the last hour didn’t exactly provide closure, it’s hard to argue the end came prematurely.

Indeed, the producers were clearly leaving their options open, even if the title would have been something of a misnomer going forward. Still, given how clearly the storytelling had run out of gas CBS’ decision felt like a mercy killing, on a show that had already crammed a whole lot of violence into its small town.

As observed at the outset, Stephen King concepts generally haven’t fared terribly well on television, with a few notable exceptions (“The Stand” comes to mind). And while the concept was intriguing, season one signaled some of the problems to come, even before this season’s absurd pod-people twist, introducing an alien-influenced cabal, The Kinship, which exercised control within the Dome and gave birth to a plucky resistance.

Like any good bug-like alien invader, that also meant birthing a Queen. First that title belonged to Marg Helgenberger’s character, then Kylie Bunbury’s Eva, who mated with Barbie (Mike Vogel) to produce a perfect replica of herself, only with light eyes and a hipster wig. In the finale (and SPOILER ALERT if you haven’t watched), Barbie seemingly caused the Queen to plummet to her death, after Joe (Colin Ford) sacrificed himself to bring the Dome down.

At that point, the government came rushing in, determined to sweep the whole aliens-among-us thing under the, er, rug. That allowed for a one-year flash forward, and the fleeting possibility that the Dome’s captives might really move on with their lives, with Barbie and Julia (Rachelle Lefevre) finally settling down.

But no, there were too many minutes left in the episode to buy that, and of course the hour ended on a cryptic note, with the Queen resurfacing, even finding a new egg. Besides, when Big Jim (“Breaking Bad’s” Dean Norris) said wryly, “I’ve seen enough bad movies to know” the Queen might have survived if there wasn’t a body, well, after three seasons, he really should know.

Written by exec producers Neal Baer and Tim Schlattmann, the hour featured several key deaths – which included Jim having to kill his own Kinship-controlled son (Alexander Koch) – but the series had veered so far off the rails it was hard to care. The most risible moments in the closing weeks involved Barbie talking semi-affectionately about his “daughter,” like she wasn’t an alien who had preternaturally grown to adulthood and become a duplicate of the woman with whom he’d been sleeping not so very long ago. But why split perfectly coiffed hairs?

Usually, when a series ends these days without finality – or at least the creators being able to clearly put their finishing imprimatur on it – there is understandable griping, like reading a novel without a final chapter. In this case, with the audience having dwindled (and many lingering, one suspects, out of morbid curiosity) and the show having drifted further from its literary origins, any such outpouring would be misplaced.

Ultimately, “Under the Dome” would have been much better off, in hindsight, if it had built toward and delivered a genuine ending in its first year, following the limited-series format that has been adopted elsewhere. That certainly would have allowed for a more direct adaptation of King’s lengthy novel.

CBS deserves some credit for having kept the lights on in the summer with its serialized dramas, although “Extant” (another Steven Spielberg-anointed sci-fi project) and “Zoo” haven’t exactly adorned themselves in creative honor either. Whether that means simply tinkering with the formula or a more dramatic overhaul, one thing seems as clear as the Dome itself: It was time to officially turn out the lights on this dimming “Dome,” which really was a bad egg.