Lots of new news on Gunslinger. Here is an updated and more detailed synopsis:

In 2012 the world economy collapses.
In 2014 all first world governments crumble.
In 2015 the power and lights go out.

2018, Wisconsin, USA. Communities live in fear, protected by paid gunmen. We cut to Jake (former engineer) now hunting for food to feed his family. He sees smoke in the distance and realises that it is
his home. A gang, led by the psychopath Brody, has attacked and murdered his family.

Seeking revenge, he enlists his ex-military brother ‘Sev’ (Josh Hartnett) to track and hunt the killers.

A series of snowmobile chases, shootings and deaths lead us to a climatic showdown in a nearby town. Jake and Sev must take on the whole town in a big finale shootout, aided by local barmaid ‘Kate’ (Anna Anissimova).

Source: SCFilms

An article that mentions the producer and actress attached, the finance and production of the film:

Simon Crowe’s ambitious new outfit SC Films has closed a slew of deals on its Josh Hartnett vehicle Gunslinger in advance of the AFM. The $16 million post-apocalyptic thriller, has now been pre-bought by Wild  Bunch for Germany and Benelux, Scandbox for Scandinavia, Odeon for Greece, and ECS for the Middle  East

Shooting is due to begin early next year on the project, which is backed by financier Future Films. Chris Nahon will direct, Mark Williams (The Cooler) is the producer and Anna Anissimova will star alongside Hartnett.

Targeted at the 14 to 30 year old audience, Gunslinger is set in the near future, after the world economy has collapsed, governments have crumbled and the power and lights have gone out. Hartnett is to play Jake, a former engineer, out for revenge against the psychopathic killers who murdered his family.

“The pre-sale market is not dead for the right movie,’ an upbeat Crowe declared in Santa Monica this week.“Distributors are going to be cautious because cash flow is the really problem for everyone, but if they see a movie  that has potential to be profitable on all the different levels of release, then buyers are going to buy.�

Source: Screendaily

And lastly, a poster (already!) for Gunslinger. Josh looks like what he did in Lucky Number Slevin =)