This seems familiar...

Almost like I've lived it... often

Outpost is a low budget British horror film.

Something about Nazis experiment on human corpses and soldiers having to fight them off. Not really that familiar I guess.

A trailer and 4 minutes of the film available after the "read more".

....Once at the outpost, the men make a horrific discovery that turns their mission on its head – the scene of a bloody and gruesome series of experiments, carried out by the SS in Reality shifting and Reanimation during World War II to create invincible soldiers. (See Die Glocke) Amidst the carnage, they find a survivor (Johnny Meres)...

Outpost movie trailer:

And here is 3:55 excerpt from Outpost:

I first found out about Outpost here which had the following snippets:

So....A while ago I got my hands on a B-Grade move called "Outpost".....

In short, a small group of mercenaries are led to an old Nazi WW2 bunker where various experiments were done. After a while the team is attacked by none other than Nazi Zombies!

The final moments of the film involves the team strategically falling back through this bunker while a horde of invulnerable nazi zombies come to kill them. Funnily enough, this movie was released about 8 months before COD:WAW was....maybe this was the inspiration for the original zombie map?

The film also features a "generator" device which can disable the zombies with, surprise surprise, an electricity style effect. Although it fails after a short time due to some malfunction or maybe lack of power. I'd be willing to bet money that Treyarch have been watching this movie (points at the temporary electro shock defenses in Verrukt)....