A fantastic old school shooter with some of the best visuals in the genre and a storyline that is utterly bonkers, featuring time travel, genocide and a vengeful bison in a wheelchair.
The health system is similar to Crank whereby a timer is always counting down, and the only way to increase it is to shoot more bad guys (getting hit yourself results in a time penalty). You also have a limited but rechargeable ability to slow down time which makes the bullet hell portions of the game a lot easier to deal with.
As such it’s much more accessible to people who are new to the genre or who (like me) are put off by the difficulty of other shooters (e.g. http://www.youtube.com/watch?v=CrPLhATu9pU&feature=related)
It’s a perfect blend of fun, skill and style.