I lasted just over three hours on my first day in the fictional Russian state of Chernarus. I'm told this is quite good, but just leaving the beach alive was victory enough for me. I pulled free of the bloodied arms grabbing at me, but it was dumb luck that found me sprinting frantically up a steep, dark wooded hill until I lost the gray-faced pursuers in the thickets and weeds. Exhausted, I lay down to hide but discovered I was wounded and bleeding. By the time I learned to use my single bandage, I was bleeding out.

A steep learning curve, but I had absorbed my first lesson: Stay out of sight. My second lesson occurred later that day, when I realized the sound of my rifle was a dinner bell. I died in the street with my legs broken, drowned in a mob of screaming madness. DayZ teaches by brutal example. Exposition is nonexistent, but once you learn something, you tend not to forget it.

Military simulator ARMA II's moddable, sandbox nature spawned unexpected offspring early this year when Dean Hall released his unassuming, open-world, zombie apocalypse mod for the game. 1.3 million users later, he's begun development of a standalone product destined to outsell ARMA II itself. DayZ is an honest gaming phenomenon.

You play from ARMA's familiar third-person cover-shooter perspective, a view you'll come to prefer over first-person for the situational awareness it provides in this game, especially under cover. The generally unpleasant, janky feeling of ARMA's engine is preserved, but works in DayZ's favor as imprecise aiming, motion delays, and other sloppy details only reinforce the survival horror mood the mod works overtime to present.

The goal is simple: Stay alive. You'll need to find water, food, shelter, and eventually weapons. Likely in that order. You can salvage preserved food, but hunting is also viable option. Blood transfusions restore lost health and cure ailments, but there's a catch–they require the assistance of another player to perform. In DayZ, fellow humans are potentially far more deadly adversaries than their undead counterparts. They lie, they cheat, they steal and they will kill you for a can of beans. Or, they just might save your life. Until you lower the gun and ask, you'll have no idea of knowing for sure.

Installation is a different kind of horror show. Both ARMA II and the standalone Operation Warhead are required for DayZ, and you need to complete a seven-step process that outlines the various installations, updates, launcher shells, and more before you can be eaten alive. Many things can go wrong along the way, and often do, judging by the pleas in forums dedicated to the game.

The code itself is famously unstable, described somewhat modestly as in an "alpha" state, but the biggest problems are gamers hacking the servers with bizarre, session-ending exploits. I experienced these frequently enough for it to be a legitimate concern, although the development team regularly takes measures to crack down on this behavior. Performance-wise, DayZ is no better than ARMA II, so plan to pack a firecracker of a system if you want smooth framerates and some visual pop. Laptops and milquetoast desktops won't stand a chance. Consider the system requirements a bit optimistic.

In this era of Pride, Prejudice and Zombies, it's shocking that it took so long for a game of this nature to be made, especially given the success of other games with similar themes but radically different mechanics, like Valve's Left 4 Dead series. We have zombies on prime time, zombies fighting plants, zombie sex stories, zombies everywhere. Why it took one guy doing it for free to make this happen is a question for the gaming industry to ponder as they watch the number of players continue to grow.

For those on the fence deciding whether to try the mod or wait for the standalone version, I advise getting involved now. There's nothing more uncertain than unwritten software, and by the time Dean's team gets into gear, the moment may be over. DayZ is here, now, and it's free. There's no reason to wait. The hungry residents of Chernarus are dying to see you.

Note: The "Try it for free" button on the Product Information page takes you to the vendor's site, where you can download the latest version of the software.