nMars - Core War MARS for .NET 

nMars - Core War info

Core War is a programming game in which two or more battle programs (called warriors) compete for the control of the MARS virtual computer (Memory Array Redcode Simulator). These battle programs are written in an abstract assembly language called Redcode. The object of the game is to cause all processes of the opposing program(s) to terminate, leaving your program in sole possession of the machine. [from wikipedia]

If you are stil not sure what Core War is follow links below, but return back :-)

Core sites

News and Groups

Hills

Software

People

Documentation

Archives

Warrior collections

List is not yet satisfactory, if you missing your favorite site here, please let me know.