This is for Descent v1.4a. If you don't have v1.4a, patches are free, you know. I'm not sure if that 'a' means anything or not.

First open up your ol' hex editor and open the descentr.exe file. You may want to make a backup first lest you screw up. Go to offset 0x9D570. Here should be the bytes E8 A1 D6 02 00. (If these aren't the five bytes that are there, then something is wrong, so you'd better not try this.) Replace all five of these bytes with 90. Save the file.

Start up Descent and begin a game. Notice the ship doesn't move up and down in an annoying manner. Yea! You may now play Descent without getting motion sickness.

This is for Descent II v1.2. If you don't have v1.2, patches are free, you know.

First open up your ol' hex editor and open the descent2.exe file. You may want to make a backup first lest you screw up. Go to offset 0xC9BBE. Here should be the bytes E8 F7 04 04 00. (If these aren't the five bytes that are there, then something is wrong, so you'd better not try this.) Replace all five of these bytes with 90. Save the file.

Start up Descent II and begin a game. Notice the ship doesn't move up and down in an annoying manner. Yea! You may now play Descent II without getting motion sickness.