Patch 1.1 - Steam version is already patched and the humblebundle DRM free version too.
W=MoveForward | set Engine.PlayerInput MouseAccelThreshold 0.0 | set Engine.PlayerInput MouseSmoothingMode 0
MouseX=IF_MOUSE_LOOK_ENABLED Count bXAxis | IF_MOUSE_LOOK_ENABLED Axis aMouseX Speed=2500.0
MouseY=IF_MOUSE_LOOK_ENABLED Count bYAxis | IF_MOUSE_LOOK_ENABLED Axis aMouseY Speed=2500.0
RightMouse=ZoomCycle | onRelease ZoomCycle
Note: This works for walking and crouch as well, changes their lines to (in this case the buttons are Shift and CTRL)
Shift=Walking | onRelease Walking
Ctrl=Duck | onRelease Duck
Launch the game with -dx9 parameter.
In Arcadia (the fifth level), do not have the Scrounger tonic equipped around the time you search Langford's Safe. The safe holds a required quest item. To fix this issue, you must reload an earlier save and remove the tonic by visiting a Gene Bank. Once you have the item from the safe, you can safely use the Scrounger tonic for the rest of the game.
In Fort Frolic, do not leave the level using the Bathysphere that you begin the level next to. If you do leave Fort Frolic using that Bathysphere then when you return to Fort Frolic the curtain that needs to be open to perform the "Cohen's Masterpiece" quest will be permanently closed. If this happens then you cannot get to the Fort Frolic exit Bathysphere to progress to the next level.
In Fort Frolic, it is possible to get trapped in Rapture Records. When trying to kill Silas Cobb, don't use the Hypnotize plasmid. If you do and the Big Daddy kills Cobb before he's able to perform a scripted task, you must return to the main map by killing yourself. (The Incinerate! plasmid at your feet works well.) Reloading an old save is also an option.
If your saves to do not go far enough back then the first two are game-ending issues. Technically, modifying the save file or using a trainer would also fix the issue, but neither solution has been documented.