Never mind the war between humans and orcs. The bigger problem with the first event movie from Duncan Jones, who impressed so much with sci-fi brain-spinners Moon and Source Code, is how to unite the tribes of hardened gamers, fantasy fans and non-aficionados in support of a franchise-initiating film adaptation. It's a tall order and, despite evident passion for the material, Jones rarely musters the persuasive punch needed to bridge the gaps.

Jones's main sell is the impressive mix of soul and CGI he invests in his orcs, gargantuan warriors whose land is dying. Forget about the drooling horrors in the Lord of the Rings films, these beasts have well-formed social and familial ties (and cute babies), not just over-formed biceps. The foremost orc here is father-to-be Durotan (Toby Kebbell, emoting through performance capture), who joins an attack on the hippie human world of Azeroth, but who believes peace can be brokered without breaking too many heads. Sadly, his skull-pulping clan-leaders beg to differ.

The human story-strand is limp by comparison. Although Travis Fimmel endeavours valiantly as the knightly Lothar and Paula Patton grapples gamely with panto fangs as a half-human, half-orc intermediary, Ben Foster overdoes it as a hammy wizard.

Jones commits unapologetically to this high fantasy world of gryphons, portals, spells and lofty dialogue, but the stress on world-building tends to outweigh both motion and emotion. The swift, swarming battle scenes are too brusque, too busy to excite. With emotional interest even scarcer, we're often stuck with the worst of both worlds: a plot that feels both too rushed and, sometimes, too dull to engage. Hints of humour help, largely conjured by Ben Schnetzer's boy wizard, but more might have leavened the overstuffed load. Without it, the drama lumbers towards an admittedly nifty tease for a sequel that might never emerge.

General release from Mon 30 May.