I've always suffered from motion sickness while playing these old Doom-like fps games. Over time I've pinpointed exactly what causes it. It's the wavy vewport bobbing while moving. Only games that have this kind of viewport bobbing make me motion sick. I can't be the only one. So, for instance, Daggerfall, Wolfenstein 3d and Quake are fine, while Doom and Dark Forces make me motion sick.
I would like an option or a console command to disable it.