OH NO!!!?!? CHEATERZZZZ
In all seriousness, open source software is a beautiful thing, without it, we would not have made half of the software advances we have in the last 20 years. Besides, how could you be so surprised that people sat down and made a civilization clone? It has been done many times in the past, and it will continue in the future... Why? Because they have the right as intellectual, independent thinkers, that's why.
If anything, these programmers should be patted on the back for selflessly providing a free civ clone for people to play and for encouraging growth.