I thoroughly enjoyed the combat, customization, and open-world elements in Crysis 1 and Warhead, but , on many occasions, as I found myself spending hours simply exploring the world, I kept wishing there could be some sort of additional incentive for doing so. Not in the form of achievements, but actual physical rewards that could be enjoyed during gameplay. For example: secret weapons you cannot collect during the normal playthrough, suit skins, a dog-tag collection-reward system (i.e. collecting hidden dog-tags/tokens/whatever grants you currency for purchasing items in a secret shop?) How awesome would it be in Crysis 2,to find a hidden passage somewhere in a building off the beaten path, where you could find some hidden costume/, weapon, visor, vehicle, or something else? I think it would be an excellent addition to the game. The world is going to be big and beautiful,so people are going to explore it anyway, but some treasure-hunting incentive would make it even better.
Cheers