Bullet weapons however, do not recharge, nor are mid-mission reloads possible. Weapons can sometimes be picked up off the battlefield, at the expense of dropping the currently selected secondary (or current primary) weapon. One advantage of this is the ability to pick up a weapon too heavy for the Runner to normally use, at the cost of drastically reduced speed. Missions vary from assaults, infiltrations, recon to defending bases or convoy escorts. Combat is fairly straightforward, with the ability to tilt and pivot the Runners "head" (and sometimes the entire torso) to target enemies not directly ahead of the player. This is especially useful when attempting to take down rather frequent encounters with airborne units. The two main features are locational damage and deformable terrain. Locational damage applies to all enemy units and buildings, allowing the player to target legs to quickly destroy or disable enemies, to destroying the head, which in most cases is not actually fatal, but has practical or comedic purposes. The basic bipedal walker enemy without its head has no weapons, but it will continue to walk around - blind - bumping into the player or buildings. Deformable terrain is primarily a visual pleasure, with little practical use. However, persistence or clever thinking can reward the player with a tactical advantage. shooting at the edge of a hillside can create a "notch" to fire down onto or up at targets. The biggest deformation possible is the nuclear missile. Accompanied by a white flash, it will not only obliterate almost anything within its wide explosion radius, it also creates a large crater and sends out a shock wave along the ground, using the terrain as a moving "wall". Not only does this serve to trap anyone surviving the blast inside a deep, burning crater, but it can be used as a mountain-destroying device, or to rip a chunk out of just about anything that stands in the player's way. Any terrain deformation can be seen on the game's 3D, real-time map screen. In total there are 7 Planet Runners available to the player: Gnat, Stormguard, Invader, Warthog, Raptor, Retro, and Shiva. Each class of Runner also has its own onboard computer, with its own voice overs and in some cases, a different view on things. The heavy runners speak in first person ("I have damage to my hull"), where the lighter runners are more formal ("Warning: Damage