At first, you envisage an amazing scenario whereby Opposing Force makes you use these human assets throughout. That, lamentably, is not the case. Once used to solve a certain puzzle, there's usually a scenery-based obstruction that prevents your new friends from following. You then trudge though corridors on your lonesome, until Opposing Force decides to spring a similar puzzle. This is symptomatic of the tempered ambition that seems to pervade every moment in Gearbox's add-on pack.

Take, for example, the new toys that you have to play with. The new guns are okay, but they're hardly spectacular. The one really interesting new addition is the Barnacle. You know the aliens that hang from the ceiling, grabbing unwary passers-by with their super-sticky tongues? Well, it's one of those, in a useful, hand-held form. It doesn't inflict damage upon creatures when you 'fire' its tongue outwards, but it can be used to pull yourself towards certain objects, like an unorthodox grappling hook. If you can see 'organic matter' in some lofty position, you can fire it and... whoosh! You're there! Unfortunately, you can only use it when the appropriate 'organic matter' is in position. So, again, it's a feature that promises much but is only of relevance or use in a few context-specific situations.

Opposing Force introduces a few new aliens, of course, but, tellingly, it's the introduction of each that works best. By well-considered usage of sound and set-piece alike, it insinuates that the most terrifying aberration ever to stalk the Earth lies around the next corner. Within 10 minutes of these artful debuts, however, they're just another monster model to dispatch. They're not particularly outstanding to behold, either - especially when compared to the excellent aliens created by the Valve artists.

And the rest? Well, it's just Half-Life, really.