While in the midst of delivering another goofball space opera for Marvel’s Cinematic Universe, James Gunn has secretly been crafting a horror comedy that’s truer to his offbeat origins. ‘The Belko Experiment’ plays like some sort of unholy mix between ‘Battle Royale’ and ‘Office Space’, both harshly cynical and goofily fun.

This is the sort of horror flick that doesn’t generally get made in Hollywood. But a ‘Guardians of the Galaxy’-sized hit certainly helps, so Gunn managed to squeeze this dirty thrill ride through the system. Hopefully, it’ll find its way onto screens to upset and entertain soon enough.

The title experiment takes place in Bogotá, Colombia, where an office building worth of cubicle drones have been imported from the U.S. to work on menial tasks, flirt, and banter awkwardly. You know, the usual office stuff, just in the middle of South America for some reason. One typical, boring day, the staff finally learn their true purpose. All of the windows and doors are blocked by metal shudders and a voice announces that they must kill someone or three will die at random. No one believes it’s real, but then the corpses pile up. After that, everyone is told that 20 staff members must be murdered by their colleagues or 30 will be killed randomly. Obviously, things get a bit messy from there.

The movie dabbles in the darkest recesses of human nature. Since the script is by James Gunn, a certain morbid wit and eccentricity come along with the scares and bloodshed. Directing duties were assigned to Greg McLean (‘Wolf Creek’). The humor is on-point and rooted to character, but the horror remains deathly straight. Blood is shed liberally. Bodies pile up. Character actors like Michael Rooker and John C. McGinely gamely steal as many scenes as possible. Laughs stick in the throat. Morality is muddled and blurred. Cynicism reigns supreme. Even if a happy ending is possible, there’s no way it will be pleasant.

‘The Belko Experiment’ won’t exactly be everyone’s idea of a good time. Even those who do love it might be a little disappointed by the sheer volume of obvious influences behind the high-concept horror picture. However, for those twisted few destined to dabble with McLean and Gunn’s bitter little pill of sleazy/smart entertainment, there’s fun to be had. Clever, funny, brilliantly acted, expertly constructed and vicious, it’s a horror/comedy that lives up to both halves of that troublesome genre. The movie will likely earn some sort of cult fondness in the future, and plenty of people will feel badly about themselves for being entertained. Now that’s just a good time horror flick.