As far as alt-history goes, "What if the Russians had found Hitler's body before the Germans burnt it to ash?" is a pretty modest detail to change. I'm not spoiling much by saying that this is what Ben Parker's Burial hinges on, since it's heavily implied in the trailer and is right there in the official synopsis for the movie.
The Russians extract the body from the bunker where he topped himself, and Stalin orders it brought straight to Moscow under strictest secrecy. They want to keep the news secret for as long as possible, and, given that Russia seeded misinformation about what really happened for months in the real world, well... it's less ridiculous than it sounds. The catch, and the premise for this movie, is that to keep as low a profile as possible a small group of soldiers is entrusted with the task, and need to make their way from Berlin to a train station in Poland.
While Poland is occupied by the soviets, it's not exactly secured. Despite their precautions, such as burying the box Hitler's body is being transported in every night, the Russian detachment is soon ambushed by werewolves.
And this is where I need to spoil the movie a little to keep talking about it. For all its genre red herrings, Burial really is a war movie, although a very pulpy one. As fun as soviet soldiers vs. vampire Hitler and Nazi lycanthropes would be, here they just bury the body so that if they're killed no one will find it, and werewolves just refers to a true-to-history late-war Nazi irregular troops that were trained to use guerilla tactics in the wilderness.
Not that verisimilitude is high on this movie's list of priorities. The Werewolves fight with hallucinogenic gas, for starters.
So! The Russians are left without motorized transport early on after an ambush, and the second-in-command's (played with palpable douchiness by Dan Skinner) first decision is to split the group so he can head to a nearby village for some R&R. Which, it being wartime in an occupied country, is of course an euphemism for looting and raping. While separated both groups are ambushed by werewolves, and left to regroup in an old farm with a semi-sympathetic polish partisan (Tom Felton) where they are besieged by the Nazis, who are led by a couple of SS types who know about the dead Führer and have their own aims for it.
It's a cheap-ish but great looking film. It unfortunately doesn't make great use of its post-war setting - the shelled-out husk of Berlin is soon left behind as the action moves to the Polish forests. And speaking of action, the (many!) shoot-outs and stabbings here don't always make sense - there's obvious tactics gaffes on both sides (particularly on the first few night-time ambushes; If the bad guys hadn't fucked around with the hallucinogenic gas and just used their guns and explosives, the movie would be a hell of a lot shorter!) But other than that it's all fun, compelling and very bloody.
The script, likewise, has some weak spots but mostly it's pretty smart. Parker has a good ear for dialogue and the movie has several themes interwoven through it: for example, the more traditionally heroic Russian soldier is a bit deflated when he's forcibly shown that the polish locals might just see the Soviet army as another occupying army, not as liberators. And a framing story involving a neo-nazi, as well as the werewolves' agenda and a few discussions about who gets to write history, gives a bit more heft to the whole "make Hitler's fate be known" enterprise.
Also, at one point a nazi brags about the Ahnenerbe to then immediately coo about what a lovely skull his captive has... I'm going to cut a lot of slack to any movie with a nazi pseudoscience joke as weird and funny as that.
The acting is good throughout. Felton, Charlotte Vega (as the protagonist, a resolute Russian intelligence officer) and Barry Ward (as a heroic and particularly death-resistant soldier) make for very likeable heroes.
I'm not going to lie, I'm still a bit annoyed at the genre misdirection going on here. But it's plenty good as 'just' a war story, and the tone is grim and brutal enough to place the whole enterprise into at least horror-adjacent territory. Not the best war movie about a small group of beleaguered Russian soldiers stranded in enemy territory I've seen (that would be The Beast), but still - pretty good.