I watched a GDQ run of this game and saw the runner skip the entire first level. I play on version 1.4, and I got the game from MyAbandonware.

Hello!

If you are interested in speedrunning this game I can help with any question you might have.

Are you using Dosbox?

Yes, I am using the latest version of DOSBox.

Anyways, I'm really confused about most of the tricks runners use. I've seen the start of a GDQ run, paused, and thought to myself: Wait, how'd he just run past that guard?

So the jumps over the guards usually require a setup. So the moves directly proceeding the jump are important. For instance the first jump: you must let yourself down from the first room and then immediately jump into the next room. that causes the guard to move forward a little. On Youtube you can change the playback speed. watch the first guard jump at .25 speed and try to get it.

Jumping over the guards is an advanced technique I wouldn't start off trying the jumps.