Does the server or my game determine:
if I need to reload
how much energy I have
what speed I can move at
where I am located
how much damage my bullets do
The answer for any FPS programmed 10 years ago is the server. In crysis, the developers let each person decide. That means any idiot can cheat with no effort, and they will, on every game server you play on.
This game will not be fair, (and not be fun), until a HUGE, and I mean HUGE, patch comes out to change completely how multiplayer works.
This game was launched halfway done. I'm not optimistic it will ever be done. If you care about multiplayer, don't waste your money. I wish I didn't
single player is awesome though if that's all you care about.