Indecisive people are best off steering way clear of Deus Ex: Invisible War. While at first glance it may appear to be a straightforward, action-packed, first-person blaster in the style of Unreal Tournament or Quake III, there's considerably more going on under the bonnet here. In fact, if you were to bracket it to a specific genre, then it's a little more comfortable being described as an adventure game, with bits of action available if you want them.

Perhaps we'd better explain. Viewed from a first-person perspective, Deus Ex: Invisible War kicks off some time after the events of the original game, and puts you in the shoes of trainee Alex. She is just freeing herself from the shackles of the overbearing Tarsus Corporation and, frankly, being pulled in lots of different directions.

Thus, as you make your way through the futuristic Seattle in which Alex initially finds herself, you'll discover yourself conversing with numerous people who each have their own agenda. They'll offer rewards and inducements for Alex to take on objectives, and it's ultimately your decision which ones she takes on and who she talks to.

However, there are ramifications to think about. Every decision you make in the game, and every objective you choose to take on, will have an impact. It may be just a minor ripple, but - put simply - every task you take on that meets one person's agenda will naturally conflict with another's. Over time, and through your decisions, you will define who your friends and foes are, and with some big and influential factions at work, it's best to tread quite carefully.

These aren't the only decisions you have to make, though. There's no single set way to take on an objective and a willingness to consider alternative approaches will work in your favour. One early example is when you're tasked to break into an apartment. This you can do by befriending its owner, dropping the janitor a backhander or simply breaking in. Each approach achieves the same goal and could potentially have slightly differing consequences.

More predictably, the game lets you choose between action or stealth. The latter, ever since the original Metal Gear Solid appeared on the PlayStation, has become an overused gaming mechanism, although in this case it's quite an effective one.

All-out action is also a perfectly valid tactic, albeit one that attracts a lot of attention. Still, there is a third way. You can simply talk to people. While occasionally long-winded, conversations can open doors (both proverbial and physical) a little more easily at times, and generally it's a mixture of all three approaches that proves to be the most effective.

In some ways, Deus Ex: Invisible War is an overwhelming game and for many people it's not going to be quite what they were expecting. Clearly fans of the original are in for a treat, although the game world is a bit smaller this time round and not quite the major innovation its predecessor was. Likewise, action-fiends may not warm to the numerous scenarios where the best approach is to holster your weaponry and try some different approaches.

That's not to say that Deus Ex: Invisible War isn't a significant achievement. It most certainly is. When it hits top gear, this is an engrossing, intelligent piece of software and one that rewards real effort by the player.

Sure, there are times when it feels a little clunky - the inventory screen isn't the most helpful, for instance - and long-winded. But that's a small price to pay for a game which, while not hitting the heady heights of the original Deus Ex (which is now available for a mere fiver if you missed out first time round) nonetheless ranks as strong entertainment.

This is not a dish to everyone's taste, yet it's undoubtedly a deep, immersive and highly entertaining challenge for those who take to its flavour.