Perhaps Warzone's most intriguing feature is the way new units are created. First, the story conceit is that you belong to a group called The Project, which is attempting to rebuild the Earth after it's been devastated by a nuclear attack. New technology is really pre-Collapse technology, and it must be discovered on the battlefield. Once something new's been discovered, any vehicle can pick it up; this makes the tech available to be researched. You may research any tech you discover, but you can only research one advance at a time, and you can't queue research items -- they must be started explicitly and individually. Once researched, the new improvement can then be added to your existing vehicles and buildings.

To create new units, you access the Design tool. This tool lets you build a new vehicle from the ground up. You start by selecting a chassis from a list of pre-researched parts, and each one considers factors like weight, armor, and engine output. Your next selection pertains to the type of wheels you want, and the third consideration is what sort of weapon you want mounted on the vehicle. Certain new technologies, like flamethrowers, must be explicitly added to a design, while others, like upgraded bullets, are simply there by default in every vehicle that pops out of production, even older models. Once you've developed a new vehicle, that design is always available to be produced, and can be custom named.

The vehicles themselves are fairly stock at first, but the later missions really open up a wealth of options. Rather than the standard unit methodology, where commands are issued through keyboard presses, right-clicking a unit will bring up a menu of movement/reaction options, like firing range, aggressiveness, pursuit, when to return to base for repairs, and intriguingly, a choice for "Recycle".

Another item of interest is the way vehicles earn experience by surviving combat. They'll rank up according to the following order: Rookie, Green, Trained, Regular, Professional, Veteran, Elite, Special, Hero. You'll see rank bars next to each particular unit as they earn them. Each successive gain in rank confers better stats to the unit; Speed and Accuracy are raised, while Enemy Accuracy and Enemy Damage Taken are lowered.

Miscellany: Trucks can repair buildings, but only Repair Turrets can heal vehicles. The nice thing about these units is that they will heal a whole group of vehicles one by one without needing explicit direction; just click on one damaged unit, and the RT will go after the other damaged units when it's done with the first one. When crowded, vehicles will move out of each others' way, but not terribly intelligently; however, Trucks and RTs will continue to make repairs while they're moving, so it's not that much of a big deal. And when a unit leaves a group to return to base for repairs, it drops its group designation. I understand why this happens, but it's still a pain to have to re-group single units to the larger convoy every time it happens.

All in all, Warzone 2100 is as playable as its ever been, and of course it's free, which makes a great number of things okay. Grab it today!