In Machines at War, you manage not only tactical forces, but the military-industrial complex behind those forces. You begin with a small amount of resources that you can deploy to grow your wealth (by building ore diggers), construct factories to build offensive machines and repair vehicles, build power plants crucial to their operation, erect defensive walls, construct airports that provide you with an airborne force, conduct research and development that provide you with more powerful offensive and defensive tools, and send out recon units. At the beginning of each game, you can also dictate the geography -- from desert to frozen tundra to forest, some of which determines how far you must go -- and fight for -- crucial resources. Finally, you can dial in your skill level, from newbie to expert.
This ranks among the best $19.95 I've ever spent. For awhile, I struggled to hold my own. Gradually, you gain insight and skills. After several weeks of playing, I've reached the point where I can win every game. So it would be interesting if the computer opponent had greater skill levels to provide some surprises and sneak attacks.
Still, this is an entertaining shareware offering that is recommended.