hello the people,
I have a problem with the jump in weightlessness
on the level plasma gun.
I cant jump on the platforms.
Sorry for my light english.
I have seen on you tube jumps more effectives...
Thanks for your help

Try enabling VSYNC (vertical synchronization) in the graphics options.

I'm under the impression that character physics aren't perfectly framerate independent in Quake 3 engine games, so if your framerate is extremely high you might find that jumps either go too high or too low (or maybe the wrong distance horizontally).

Thank you for the answer

I don't think frame rate is the issue. While failing a jump multiple times and getting annoyed, I thought finally in desperation, hmmm maybe I need to hold the run button down to do a running jump. Sure enough, those seemingly impossible jumps were now easily makeable.