[diablix]

I know it's been a while but since the people are still asking about it here is how I did it.
I decided to simulate on-ice effect, this is the closest effect to the real friction I could achieve:

PHP Code:

new g_bOnIce[MAXPLAYERS+1];

public setIceFeeling(iClient, iOnIce=1) g_bOnIce[iClient] = bool:iOnIce;

public OnGameFrame(){
    for(new i = 1 ; i <= MaxClients ; i++){
        if(g_bOnIce[i] &&  IsClientInGame(i) && IsPlayerAlive(i)){
            if(GetEntityFlags(i) & FL_ONGROUND){
                new Float:fVel[3], Float:fJak;
                Entity_GetAbsVelocity(i, fVel);
                fVel[2] = 0.0;
                new Float:fSpeed = GetVectorLength(fVel);
                
                fJak = (fSpeed/266.0) * 100;
                
                GetEntPropVector(i, Prop_Data, "m_vecVelocity", fVel);
                
                for(new l = 0 ; l < 2 ; l++){
                    fVel[l] += (fVel[l]/fJak);
                }
                
                TeleportEntity(i, NULL_VECTOR, NULL_VECTOR, fVel);
            }
        }
    }
}