Hi, guys.
So the problem is explained in the attached gif.
When the character (type:character, bounds:sphere) jumps on the cube (type:rigid body, bounds:cube), the cube starts to shake.
I’m only doing my first steps in bge. Spent a couple of hours googling/tweaking the menus - nothing. Help, pls.
Up. Really need a solution 
Hmmm… I don’t really know. Here is what you can try doing:
-Make the Rigid Body an obstacle.
-Collision bounds for it, maybe increase the margin.
-Increase the Rigid Body’s mass.
(these might not work, just suggestions)
Good luck fixing it!
This excellent video talks about the issue. It’s not for BGE, but the same principles apply.
Thanks for the vid, very educational! I knew, that the problem should be common, not only for BGE, coz I saw the same effect in various games. Now I know it’s called “jitter”.
I was trying to find and play with the variables responsible for the things described in the vid: gravity, engine physics fps etc. but the problem is still here. The jitter now occurs in a short while after the ball jumps on a cube.
so I’m attaching the .blend file for you guys.
Attachments
jitter.blend (514 KB)
how to do that?
-Collision bounds for it, maybe increase the margin.
-Increase the Rigid Body’s mass.
none of these had taken any significant effect on the jitter
Thanks anyway! damn, spent 3 days in a row fixing it - still jitters 
I guess I’m just stupid
ok tell me…
What do you want to get/create?
Cube = rigid? you need (the effect for) it to roll? if not put it on dynamic. (this could already solve your problem)
Also i am not a fan of character physics, it is better to use dynamic type for it (gives you more control over it), but this is personal choice.
Thank you! Type:Dynamic for the sphere solves the jittering problem!
yes, but dont forget a sphere with dynamic will not roll, like it would with sphere physics.