CONTAINS SOME SPOILERS
Despite most examples of the game-movie crossover being neither huge hits nor particularly good (it's a subgenre in which Silent Hill is one of the front runners), the idea of a film version of the Halo game franchise has been around for quite a few years, with some major names attached to it. Guillermo Del Toro and Neill Blomkamp were both down to direct it under executive producer Peter Jackson; when those collapsed, Steven Spielberg apparently expressed an interest. Since then: nothing. In the meantime, there's this compilation of five 15-minute "webisodes" which were originally designed as a marketing tool for the Halo 4 game (all five are freely available on YouTube): they've now been bolted together with some new footage and released as a feature film.
I'm not a gamer, so I've had to look this stuff up, but most of the movie version of Halo 4: Forward Unto Dawn is not concerned with intergalactic war between humanity and aliens. Instead it focuses on the cadets at the elite Corbulo Military Academy on the planet Circinius IV in the year 2526, and specifically Thomas Lasky (Tom Green), of whom great things are expected due to his family's military careers, but he can't maintain discipline and follow orders. Only when giant alien killing machines show up does the film change gear with a mere handful of surviving cadets running through the forests to get to the evacuation point as the Academy - apparently the only population centre on Circinius IV - is destroyed.
It opens with a pretty spectacular derelict spacecraft sequence, which suggests the movie is going to be a proper SF thriller in the Event Horizon mould, and includes the film's sole mention of The Covenant, "a theocratic alliance of aliens" (at least according to Wikipedia, as this is not made clear in the film itself) which are apparently the villains of the game series. Sadly, all this is used as a framing device for veteran Commander Lasky's flashback to his training days, so it ends up like a softened and less satirical Starship Troopers with none of the giant bug material, and with Predator-like warrior aliens showing up for the final battle. It seems unlikely they were trying to echo Young Kirk from the Star Trek reboots, given that the film is really a feature length advert for an Xbox game, but that's almost what it feels like. The mystery of what happened on the freighter Forward Unto Dawn, why the ship's AI computer has turned into a CG-animated woman, and who's in the sole surviving cryo tube are sadly not explored and they would have made for a much more exciting and imaginative film than Lasky's reckless past.
Once it gets going - the aliens don't turn up until well over the halfway point - it is slightly more fun, with action sequences, character redemptions and unexpected casualties crammed into the final 30 minutes. It's enjoyable, it's certainly well enough done (it's directed by Stewart Hendler, who made the glossy but empty remake of Sorority Row a few years back), and the CG effects are a lot better than expected given the relatively meagre $10m budget, but the structure lets it down somewhat, with the visually striking opening never resolved and the interspecies war which is apparently the heart of the Halo series taking a back seat to Lasky's Academy struggles. Whether it will ultimately lead to a full-fledged Halo movie, remains to be seen.