The first thing we did was go through a rundown of the basic technology behind Half-Life. Ken Birdwell was kind enough to show us the work he's been doing with the skeletal animation system, focusing on the player models we'd see in deathmatch. As is standard nowadays, each player model will hold visible weapons in their hands. The interesting part is that they have unique holding/shooting frames and animations for each weapon. The glock pistol is held with both hands at eye level, while the shotgun is balanced at waist level, with one hand on the trigger and the other supporting the barrel. The RPG (rocket-propelled grenade) is propped on the shoulder, with both hands supporting its weight. Ken had also recently implemented sidestepping frames into the player animation, so the top half of the body can appear to move independently from the bottom, making strafing much more realistic and fluid (no more sliding left and right).

As some people may already know, the player bounding box in Half-Life is separated into a series of close-fitting boxes around the body, accounting for head, limb, and body shots. These bounding boxes can be inflated (for easier to hit targets) or set as a single large box (as in Quake), all done by server variables. Regardless of model size, the bounding box for every player is of course identical. All models make use of the smoothing groups applied by 3DStudio (and many map elements do as well), and are lit realistically from muzzle flashes or dynamic lighting. As with the original Quake, any model can have separate shirt/pants colors, which can be selected by number (0-255) or from a hue slider in the multiplayer menu.

The best part about the models, however, is that the skeletal animation system is completely independent of the model. Anyone can create a single model, and then link that model up to the keyframed animation for the player character. As long as the model is of the correct proportions and dimensions, the standard player animations will be believable. What this means is that players who wish to create custom characters need only create a single model and link it to the existing player skeleton; they won't need to pose the model for running, walking, firing, or dying sequences. Simplicity is the key.