So yeah I just bought Ultimate Doom and I have no problem with the gameplay (Hey, it's Doom!) but this is my first time actually playing Doom properly (on PC that is, not PS1 or PS2 version) and after three levels I no longer can play the game because I felt nauseous and dizzy similar to seasickness. The only time I have similar experience is after playing Mario 64 on Nintendo 64. Funny thing is this only happen when I actually play the game. But if I watch a gameplay video I don't feel dizzy and nauseous at all.

Is there a way to deal with this? Or I have to give playing those games?

Also is there a way to rebind the control for Ultimate Doom? The default setting for strafing and mouse control felt awkward for me.

Experiment with the viewing angle. Often found in settings as FoV. Use a small enough monitor.

Don't play in the dark. Step back a little bit from the display so it takes up less of your vision.

Maybe you have epilepsy and/or some other similar condition.

Only a medical doctor could give you proper advice about this issue.

Best thing to do is not to play any games that cause you those feelings until after you've consulted one about it.

Also, a stable framerate makes quite a difference.

There's a few other effects to look out for, headbobbing, vingetting, motion blur, kill those off.

That's not guaranteed especially in healthcare systems such as Britains.

I would go with FoV and framerate being the main culprits or wobbly effects.

You can adjust the FOV, step back from the monitor, move you legs while playing, you could even take some antiemetic to treat the nausea like motion sickness pills or chew some ginger or take ginger pills if you don't like the taste.

It's highly recommended that you download and install GZDoom instead of trying to play the original DOS version. Aside from adding widescreen support, mouse-look, etc, you can rebind the controls, and do things that can reduce motion sickness like increase the FOV and disable Head Bobbing.

I just turn off motion blur. It looks cool but damn, I get dizzy and nauseous. Headbobbing also sucks.

Well I saw so many flashing lights without having a seizure so I'm not sure if it's epilepsy and it only happened to several gamers so far. Thank you! that link really helpful. I will start experimenting with different settings. I suspect the head bobbing might be the main culprit or motion blur.

Turn the head weaving around like Kieth Flint off.

Try playing it in a source port. I use GZDoom for all my Doom engine games. It has many options and tweaks that may help you. For example, I know some people have problems with motion sickness because of weapon swaying/bobbing, and there are options to disable it.

Edit: I just scrolled up and saw someone suggested the exact same thing. I should have read the other posts first.. :P

Turning off head bobbing is what works for me.

I have the same problem with old first person shooters. Interestingly, the motion sickness mostly appears with build engine games (Duke Nukem 3d, Shadow Warrior, Blood, Ion Fury) for me. I think it has something to do with the very quick movement in these types of games, which is probably also the reason you have it with Doom. Not rushing through the levels helps me with it. Once i get sick, i need to take a break from screentime.