there is an infinite ammo,focus and even health. but you have to complate it in doing
missions. to get infinite ammo and focus you need to beat the game on easy. and for health
it is to beat the game on either hard or normal.i hope that will solve your promblem.
there is a cheat for them. i got it from ign.com. it will help you through mission and
also has cheats for the infinite ammo,focus, and health.