Overview
If you want to learn the backstory or simply to squeeze all the juice of the game without a co-op partner, then this guide is for you.
How to do it
This is copy pasta from the Steam forums where I posted this long ago. I just thought more people would see this as a hub guide, so here it is.
Today I wanted to play the coop campaign to learn the backstory but I didn’t have anyone to play with, so this is what I did and it ended up being even more fun than single player.
You only need a gamepad and JoyToKey[a.kyot.me].
Just set up the in-game controls and the program in a way that you control both characters at the same time with the same buttons in the gamepad. Just to be clear, you have to do it in a way that you control the keyboard and the gamepad at the same time and both characters do the same when you press a button on the gamepad.
You’ll probably have to enable “Use POV switches” in JoyToKey, in the preferences tab on the right.
I have finished the whole campaign in one session so it’s not impossible, but I finished single player in hard first. I did it using only the chains and pistols.
Also, you can’t do this on consoles. One reason to feel good about owning the PC version. :>
Update: if you are having problems identifying the buttons on your gamepad in Joytokey you can try the latest version[joytokey.net] which solves that problem but may show a nagging screen every now and then on startup, unless you register it.