what modifiers work in BGE ?

i know well :

SUBSURF (50%) unstable (or random)

then i see some other that seem that work but not much tested
what other you know that work , pretty sure?

I have used the edge split modifier already.
The array modifier works too, except the start and end cap(they cause crashes).
Curve modifier works too!

Really, the Question should rather be which DON’T work in BGE. I don’t really see why you ask for the working ones if you just need to put a Modifier onto an Object, activate BGE and see whether it works or not.
Working Modifiers are a Lot:
Edge Split
Simple Deform
et cetera

The Problem is rather that except Armature no Modifier refreshes, so if you for Example control an Array’s Offset with an Empty and change that Empty’s Coordinates, the Modifier will not refresh and THAT is where it gets problematic, the Lack of Refreshness. (Not to mention, of Course, that any Modifier will drag your Performance down, so since they remain static in the GE you can apply them anyway.)

I think that is because the modifier will automatically be applied on loading into the bge (creating a static mesh).
The bge does not support the modifiers dynamical behavior (such as following other objects).

In other words:
Modifiers do not run during game play!

My thoughts:
The modifiers are an approach to get dynamic behavior into Blender (not BGE). The BGE uses the well known logic bricks for exactly the same reason.
That is no big deal on Mesh generation/modification as the BGE can use the result of applying the Modifier. These results are pretty static.

The modifiers are not accessible via BGE API. They do not even exist in-game (just their results).

The armature modifier is no exception as the armature animation in BGE is not applied by modifier. The modifier is just another way to connect skin mesh objects with armatures. The “BGE” way of doing that was and still is “armature parenting”. That you get an armature modifier is a side-effect. (Yes, you need this modifier for Blender to see the actions in preview/render.) The benefit is that you do not need to do this setup twice (one time for Blender and one time for BGE).

If at any future time the dynamic behavior of modifiers should be supported, we need:
A) Python support
B) Logic brick support
Otherwise the set-up would still be static. Which means you can’t enable/disable/modify modifiers in-game.

thanks , i know now a bit more .

the explanation of Monster is very clear , to see the modifier in the right perspective!

in fact i make confusion a bit with subsurf and armature that work in “realTime” , but for the reason that say Monster, a “side-effect”

anyway i read that moerdn want add a sort of decimator in BGE, this should be very cool to have.