Building a game on an existing IP with a loyal fan base must be a difficult and demanding task, especially if the developers have never worked with the IP before. Expectations tend to be high, and if the game is changing dramatically, the pressure will be on. Just ask the guys that worked on Metroid Prime. Tribes: Vengeance is the latest version of a game with a ten-year history (at least) and therefore comes with a lot of baggage. Good job they got a company as skilled as Irrational to work on this then, isn't it?

Previously known for the excellent 'Freedom Force' and 'System Shock 2', Irrational may not have been the most obvious choice for creating a fast paced FPS shooter. However it's this experience, dipping their toes in different genres, that gives them the credentials to make something genuinely individual. The single player aspect of Tribes Vengeance is the most immediately noticeable addition to a series that has been known as a strictly multiplayer game. It gives the Tribes universe a more rounded history and tries to establish the roots for the rivalry and hatred between Tribes and Imperials. Rather than adopt the traditional route of one hero leading the story, Vengeance paints a far bigger picture. Spanning two generations, the story is played out through multiple playable characters, often on opposite sides. In particular, one level sees you embody a cyborg assassin sent to kill the Tribesman you played in the previous section. In the hands of a less capable developer this could seem confusing, but Irrational makes the story work.

That's not to say it's perfect. The overwhelming feeling when playing the single player is that it's one big training section for the multiplayer game. For instance, there is an entire section set in an arena where Imperials play Tribals in different types of games. In the story this is presented as some kind of sporting event, but it's fairly obvious what the aim is here. It's a shame, and hampers your immersion into the carefully crafted universe Irrational has created. The actual game mechanics don't lend themselves very well to traditional FPS environments either. Tribes is a game were freedom of movement and the ability to jump quickly from point to point is key. Moving through corridors doesn't showcase these abilities very well; where Tribes works best is the free form levels that often crop up. In these, you are given a set number of goals that can be completed in any order, leaving it up to you to decide how to deal with them. This is also a far better way to hone your skills for the multiplayer game, as it forces you to think on your feet and employ a range of different tactics. Though, of course no AI can compare to a human opponent.

Multiplayer is the meat of the game as far as fans will be concerned, and it doesn't disappoint. There is a wealth of options, beyond the classic capture the flag and Deathmatch game types. The fuel cell games for example, are different, yet with enough familiar elements that they are extremely easy to learn. There are also plenty of options for getting around the, mostly pretty damn big, maps. Obviously the jet packs are back, and are fantastically implemented, with a great sense of momentum and weight to them. Combine this with the skiing ability and you can certainly make your way around in double quick time. The skiing ability was actually an exploit of the original game, which Irrational have decided to keep as an integral feature of Tribes. To their credit, maps have been designed with this in mind too; plenty of dips for skiing and hills for launching yourself from. There aren't many games that make basic movement this much fun. Vehicles are another great way to get about the place and Irrational have provided a number of options, but apart from the superb Fighter pod (a strangely shaped flying machine), the vehicles feel quite restrictive compared the movement available to you using your skis and jet packs. The tank and ATV for example work well as support vehicles, but you won't find yourself using them for long. Besides, if you are looking for more firepower, heavy armour is definitely the way to go.

The unreal engine has been used to great effect.

The game offers a range of different weapons and armour options that allow the tactically minded among you to customise as you wish. The choice of armour determines your level of mobility, health and the weapons that you can choose from. Of course, a range of different types in any team is the best way to win, though light armour is a favourite when it comes to stealing flags. Weapons are a different story with those on offer seeming limited when compared to other games of this type. It's hard not to compare the game to Unreal 2004, and beside that the weapon selection seems weak. The Spinfusor, chaingun and blaster shotgun, are all you really need, but the sniper rifle is worth a play with, being well designed and a joy to use. Still, It would have been nice to have a slightly larger range of useful weapons.

Visually, the game is exactly what you'd expect. Based on a modified version of the Unreal 2004 engine, it looks fantastic, particularly in the bigger outdoors levels. The mountains and sky look beautiful and add a real dose of reality when flying around the map. The sounds perfectly compliment the action, with weapons and jet packs filling the sky. Irrationals biggest achievement however, is the game physics. You always feel like you have full control over your jet pack and skis, and when controlled properly the fluid motion you can achieve is really something special. It's this aspect which really lifts the game beyond your bog standard FPS, turning it into something else entirely.

In the end, Tribes: Vengeance isn't everything it could if been. It's undeniably a great game with a lot of excellent ideas, however it does seem lacking in some areas. At its best, Tribes gives you a fantastic sense of freedom that you simply don't find in other FPS games, which will hopefully help to push the genre in interesting new directions. It's the implementation of other aspects, such as vehicles and weapons that just don't work as well. It's certainly worth picking up, and is sure to build a fanatical following online, but it just doesn't seem as complete as it ought to. So, if you're tired of the current crop of games, and want an FPS that's a bit different, look no further. And lets not forget that jetpacks rule...