In a Santa-decorated snow globe at the beginning of writer/director Shane Wallace’s A Very Flattened Christmas, we see a montage of different characters goofing around – and then text reading “Six years later” appears on screen, and we witness a man staggering from his car as his neck bleeds profusely from an injury, and then running across the snow with a bag full of marijuana, until finally a figure dressed as a reindeer stands over him and deals a death blow with a shovel, and the film’s title appears. There is a lot to unwrap here.

Flattened was originally a stoner comedy series appearing on Youtube at (heh) 4.20pm every other fortnight from 2016-17, and following the misadventures of Max (series creator and writer Key Tawn Toothman), his best friend Dan (Trevor Vincent Farney), their boss Dale (Mark Mannette) – who owns the roadkill collection company Furry Friends – Dale’s feckless son Dale Jr. (Blaine Frazier) and daughter Maddie (Kaemie McCanless) – whose sexual designs on Max are never consummated – all-round arsehole Rick Barnes (Jesse Bailey), and the dealer J (Naythan Smith) who keeps everyone in this Wichita community on an even keel.

Now, five years after the series ended, the whole team is back together for a feature-length Christmas reunion, and one named in accordance with the same bland A Very [insert brand name] Christmas formula that has been used literally hundreds of times for both series specials and features. The difference, though, is that this is less breezy seasonal get-together than Yuletide slasher. For after J is butchered in the snow, his unconventional funeral draws a reluctant Max back to town. From here the film plays catch up with the whole ensemble from Flattened, only to take them all out one by one. It is the ultimate execution of the principle “kill your darlings”, as all the series’ favourites are crushed, skewered or beheaded by a mysterious assailant, and Max quickly suspects that conspiracy-spouting Dan may be less trusted friend and ally than deranged slaughterer.

“Why do you think you came back?” Stewart (John Doornbos) asks Max, “What are you here to learn?” A Very Flattened Christmas seems unsure of the answer to that question. It allows us to see the toll that time has taken on folk from a show that not all that many viewers will have seen in the first place, so that its nostalgia value is reserved for a truly niche audience. It is obviously very cheaply made, overacted by all, and never particularly funny, while too silly for its horror to have much impact either. At the same time, it plays in a broad, unhinged register that may deliver the goods to anyone sharing its characters’ predilection for weed or coke. It incorporates animated sequences from Rick’s latest movie Dick Puncher Saves Christmas, which serve as a trippy mise en abyme for events around Furry Friends – and, in keeping with its small-town murder mystery, it even has Jerry-Ann (Beckie Jenek) doing an impression of the log lady from Twin Peaks, only with a Yule log.

Still, the most striking feature of A Very Flattened Christmas is its gleeful, boldly deconstructive readiness to see established characters massacred willy nilly and left as mere roadkill, nullifying any prospect of another Flattened legacy sequel – although a post-credits coda reconfigures everything to make an Easter resurrection possible. Perhaps, though, these people are better off dead, and remembered, if at all, for what they were rather than for what they have since become.

A Very Flattened Christmas is available on VoD: