Soft drink does dehydrate.. even in real life... the caffeine in it acts as a mild diuretic
Well regardless your wrong, Contrary to popular belief among mothers, soda does not dehydrate you, its a myth that exists on a faulty assumption. Saying something is a diuretic, thus it dehydrates you is false. Whats important is how powerful and how much of it you got. The diuretic effects of caffeine are minor about equivalent to that water. Soft drinks are 90% or more water, the FDA has a legal limit on soft drinks of 0.02% caffeine[energy drinks carry a different classification and thus escape that limit].
Actually studies done in the past decade have failed to give evidence that drinking soda can dehydrate you, and yet somehow the myth lives on with out any scientific backing. Water is certainly more hydrating then soda and a better choice as it lacks all the other stuff put into it.
But hey its a science fiction video game.