So I've been wanting to do a walk through for Manhunt 2 for a while now. Not a speed run but rather a kill montage kind of thing. Looking for some advice on what kind of software I should get on my PC to record it

There are countless programs for this purpose. CamStudio and Fraps are two of them.

OBS works well last I used it, If you own a Computer with a Windows 10 os it already has a pre built in screen capture and recorder.