Although the reaction to AVsP's first public airing at E3 '97 had surpassed all expectation, we knew there was a long way to go before the game we had visualised became a reality.
Jason Kingsley

After showing our early demo of AVsP at E3, we realised that the whole development process up until that point had been driven along by the changes in hardware technology (which were more significant than they had ever been, even in the turbulent history of gaming hardware).

It was decided that we had to put the brakes on this and turn things around so that we were in charge and the technology was working for us.

So, almost as soon as Chris and I returned from Los Angeles, the whole development team sat down and decided on a hardware specification which would be current at the time of release in the first half of 1999. This, of course, was an almost impossible task but, looking back, the team did quite a good job of playing Nostradamus.

During these major meetings (the biggest that we had on the entire project lasted about three straight days) everyone eventually agreed on the use of 'hierarchical models' to give life to the game's characters.

Hierarchical modelling is a process where each in-game character is effectively built from a complete polygonal skeleton, which is then 'fleshed out' by the careful placement of texture-mapped skins. This also allows for very fluid and life-like animation, as the skeleton is moved by the computer's maths processing power, rather than the traditional 'stop-frame' method. Stop frame requires an artist to draw a number of poses for a character which are then animated by the programmer, causing them to be flashed past the player's eye in quick succession (rather like a highly expensive 'flick book').

In addition to more lifelike and smoother animation, one of the added benefits of using hierarchical modelling is that it enables game characters to be blown apart in beautifully realistic ways. For example, with hierarchical modelling, it is a relatively simple mathematical process to remove a character's limb (in fact, with some of the more complex characters, you can even go so far as to amputate single fingers). It also enabled us to replace severed limbs and body parts with individual 'blood generators'.

This not only adds extra credibility to the visuals, but adds neat little touches to the gameplay too. For example, anyone playing as a Marine character has to be quite careful about removing an Alien's hand in combat. As any fan of the Alien series will know, the Alien has acid for blood, meaning that an open artery can be even more dangerous than the severed limb that it has replaced.

Now, at last, it seemed that things were finally moving towards a finished product, although we were fully aware that there was still more than a year's work to be done. The technical guys were being challenged because the updated system was new and demanded excellent programming skills, while the artists were happy because the character's new-found realism gave them another excuse to delve into Fox's archive library for reference materials... but maybe we should leave that story for next week.