Imho Earth 2140 is one of the greatest RTS of all time. I strated on the DOS version in 1999 and in that time i knew this game would be my favourite for a life time. The game was well made, not too short (it may have been longer though). Difficulty was adequate. It forced me to think twice before acting. When I got my ass kicked in a mission I just had to start it over not getting kicked, but to kick the AI :) I am giving 5 stars to the old DOS version. The new one (as being sold here) is worth 1 star for missing the AI difficulty.