> You spent 3 missles at a cost of $10 each, but you got a whole ships worth of minerals worth $60, and some more missles.

Okay, but where does this money come from? Obviously, the $60 ultimately comes from your bank account, but how does the game stay in business if you can spend $30 (you said only three missiles were fired) and get $60 worth of in-game resources, which you can then sell and convert back into real currency?

If the answer is "other players", then what happens when the player base stops growing, or begins to shrink?

None of this stuff works without a continuous stream of new marks^H^H^H^Husers.