The Engine Empire Card Game

The Engine Empire is a print-and-play card game that requires only 18 cards. From the description:

In a dystopian alternate reality, four great powers vie for control of the continent. Each Empire’s soldiers lay siege to opposing cities, while their war efforts are funded by exotic exports and ingenious inventions. Only one state will orchestrate their limited resources into an Empire Engine powerful enough to lead them to victory.

It has gotten good reviews on Board Game Geek.