Age of Darkness, even in its current state of early access is the single most addictive game I've ever played, I put in about 30 hours over the course of a few days and had to make myself shelf this for fear of ending up in a gutter somewhere destitute.

It's a distillation of all the best parts of RTS games that I enjoy, structured within a gameplay loop that constantly keeps you engaged. With every action there is the ticking countdown of your inevitable demise that you must prepare for. It is not the first game of its ilk to do these things, but for me it is the most effective