You have to be shitting me...
CS takes quick reactions, precision, communication, teamwork, and strategy. Halo takes all of those as well but not to the same degree. Sure for those on the absolute highest level both take excellent reaction times and coordination, but in CS takes much better teamwork and strategy, and most importantly game smarts. In halo maybe you need to worry about when a gun will spawn or whatever, but at top level CS each player needs to be in the right spot looking in the right place doing the right thing. Communicating strategy observating opposing rotations throwing nades at the right times etc. It reaches a depth really you only see elsewhere in games like starcraft and wc3/dota~