The game is mission-based, with each mission putting you in charge of up to ten Space Marines as they investigate a huge alien derelict that is on a collision course with planet Delvar 3. You give them orders in a tactical screen and/or take over one of them and then move in a 3D environment and fight the Genestealers just as in any FPS. You start out as a grunt obeying orders, but with successful completions of various missions, you can increase in rank and eventually be the leader of the teams. At this point, not only do you make the decisions and direct the other space marines, but you can also switch between any of the marines in the troop and control any of them personally from a first-person perspective. This is a very nice touch: although starting out like a typical FPS, SH:VGAB gradually adds more tactical options, eventually striking a fine balance between FPS and tactical planning. There is a good variety of missions in the game, ranging from destroying aliens to retrieving important items. In addition to the main campaign, you can also go on training missions, or participate in individual "classic" or "famous" historical missions in the Warhammer 40K lore. The graphics are attractive especially in FPS mode, although the Genestealers look too pixellated up close (but if they get THAT close to you, that means you are about to die anyway ;)). One of the things SH:VBA does very well is draw you into its moody, dangerous atmosphere – mostly by a lot of nice details. You will hear water dripping from burst pipes, the ever-present growl of nearby Genestealers, and battle cries from your marines. Then there's the confusion when weapons jam, troops get separated from the team, and Genestealers burst out in ambushes. It's scary, it's atmospheric, and it's incredibly immersive.

My only gripe is an unavoidable result of the FPS-to-tactical design choice. Since I prefer strategy games more than FPS games (because I'm not any good in them), I found the first FPS-only portions of the game a little too hard and boring. The only reason I persevered is because I wanted to get to the tactical-command portions, which are excellent. Fortunately, you quickly get to do this, at which point it will take some time to get used to the menu system to issue commands. It should become second nature quite quickly, though. The game is very difficult – I would say overly difficult for many missions. But if you are tired of run-off-the-mill FPS's, SH:VBA is well worth your time. Two thumbs up, way up!