HalfLife-Mods have interviewed the_s-man and DaanO from the Citizen-132 mod.

Timmay: What is the basic objective of the game?

the_s-man: There are many objectives to the Single-Player portion to the game. One of course would be your own survival, because you have been captured by the "creatures" and your daring escape puts your own life in jeopardy.
The second objective would be to attempt to save your wife. She has been taken away, and you want to rescue her. The third objective would be to escape out of the town, by any means possible. The Multiplayer objective will not be commented on at this time.

DaanO: note: the creatures may sounds much like Return to Castle Wolfenstein, but they're not monsters really. The enzymes just gives you more muscles, hair so the people that take it will look a bit odd

You can read the rest of this interview here