Is it possible to play the PC version of Left 4 Dead 2 in split-screen, where one player uses the mouse/keyboard and the other uses a gamepad?
Yes, you can. You have to make sure you know your way around the console, and playing online might or might not work.
Basically, you have to enter these commands in the console to make it work:
ss_enable 1 ss_map "map_name" connect_splitscreen localhost
You have to make sure your Xbox 360 controller is set up correctly, for that, read this forum post: Left 4 Dead: SplitScreen PC Guide.
It's possible play split screen with a non-Xbox 360 controller, but you'll need to set up your own controller configurations by editing edit \left4dead\cfg\360controller.cfg. The lines you'll need to edit are the ones starting with "cmd2 bind".
EASY STEPS FOR L4D2 SPLITSCREEN By ChilledGame
How to play L4D2 Splitscreen || Keyboard/Mouse and Controller How to play L4D2 Splitscreen || Two Controllers
Keyboard/Mouse + Controller
Two Controllers (PS4 or Xbox doesn't matter)
How to play L4D2 Splitscreen || Keyboard/Mouse and Controller
Enter 'Big Picture' mode
Click on the gear icon
Click on the option 'Controller Settings'
Ensure that your controller is configured and supported here, To this just click on what type of controller your using.
Now launch the game.
Once in the main menu, open up the game console by pressing 'Tilde' key. Once the game console is up, type the following; ss_map c1m1_hotel. This will load up the Hotel level. You can find the code to all the other maps and levels here.
When in game open up the console then type in connect_splitscreen localhost 2.
Open up the console again and type in sv_cheats 1.
Once again open up the console and type in_forceuser 1.
Finally you may need to edit the key/buttons for your keyboard and mouse.
=================================================== How to play L4D2 Splitscreen || Controllers
Enter 'Big Picture' mode, by clicking on the steam icon. A drop-down should appear, from there click onto 'Big Picture' mode.
Connect your controller and ensure that it is configured and supported on settings. After that you launch your game.
Next go onto 'options' and then 'keyboard/mouse', from there ensure that the developer console option is changed to 'enabled'. This will allow you gain access to the game console.
After this go back to the menu and hit the 'Tilde' key. This will allow us to access the game console. Once in the console, enter the following; ss_map c1m1_hotel.
Once the game has loaded, open up the console once more and type the following; connect_splitscreen localhost 2.
Hope it helps out :)