The Best Justice League Movie Everyone Missed
3. It Completely Reinvents The DC Universe
Although Gods and Monsters is very much one of the more distinctive interpretations of the DC Universe, it also conforms to a long-running tradition within DC's works - that of the alternate-earth story. Said tales were later rebranded under the Elseworlds banner, with the likes of Kingdom Come and Superman: Red Son two of the most notable examples.
As Timm said before, this tradition of reinventing DC's characters stretched back all the way to the Silver Age. But there have always been certain absolutes: Batman will always be Bruce Wayne, or an analogue of that original version; Superman will always hail from the planet Krypton as the son of Jor-El, and Wonder Woman will always reside with the Amazons on Themyscira. The settings and personalities might change, but it's very rare that the person assuming the mantle will bear no relation to the original concept, which is why Gods and Monsters is so interesting.
Set in an undesignated alternate Earth (that in itself is a travesty), Gods and Monsters brings fans the DC Universe as they've never seen it before. Superman is brought up by Mexican migrants, and that - together with his lineage - motivates him to be a different kind of hero than what most fans are used to. He uses lethal force, is skeptical of the government, and though he believes in the principles of truth and justice, he possesses an authoritarian streak that his biological father would've been proud of.
Just as Timm options an interesting Superman, he does the same with Batman. The Dark Knight of this reality is actually the Man-Bat of countless others, except here, Kirk Langstrom becomes a vampire instead. He kills to satiate his bloodlust, but he's also the most vulnerable of the trinity, with connections going back to his days at university. There's no cave, wealth or loyal sardonic butler - just a thirst for knowledge and blood, put on the straight and narrow by Superman, who inducts him into the League.
Then there's Bekka, the new Wonder Woman. The twist here is so inventive that it really can't be spoiled, but the way Timm and director Sam Liu manage to tie it into the history of the New Gods is so fascinating, and leaves Wonder Woman as the most fascinating character in the entire film.
The new trio were introduced via several animated shorts uploaded to the now defunct Machinima YouTube channel, with Batman's even showcasing the character fending off against this universe's Harley. However, when Machinima shut its doors it also pulled the plug on all the content it had been hosting, including the web-series that pre-empted the release of the full Gods and Monsters film.
Fortunately, the context provided in that series isn't essential. All you need to know about Gods and Monsters is that it presents a radically different version of the DC Universe, and that it weaves a tragic and compelling mystery in the process. The less you know, really, the better.