There is a trend in new games that you model very Highpoly ones. For the games you get a lowpoly model calculated by a software and a bumbmap to keep the detail i.e. you see that in Doom 3 and FarCry (
http://doom3.ingame.de/spiel/doom3/gegner/commando.jpg /
http://www.farcry.de/ss/pc/sshot9.jpg).