[FatallError]

How to kill a player without displaying a message on the screen.

What are the tools to control entity life in the world except ForcePlayerSuicide (client)?

[Bacardi]

Do you mean by message that kill icon upper-right corner ??
Kill weapon icon

Pre hook event player death and block it, Forceplayersuicide, unhook event.
I don't think this is bad
*edit I added bool to check that client match in player_death event. If multiple deaths appear.

PHP Code:

#include <sdktools>

public OnPluginStart()
{
    RegConsoleCmd("sm_test", cmdtest);
}

new bool:g_bSilent[MAXPLAYERS];

public Action:cmdtest(client, args)
{
    if( HookEventEx("player_death", player_death, EventHookMode_Pre) )
    {
        g_bSilent[client] = true;
        ForcePlayerSuicide(client);
        g_bSilent[client] = false;
        UnhookEvent("player_death", player_death, EventHookMode_Pre);
    }
    return Plugin_Handled;
}

public Action:player_death(Handle:event, const String:name[], bool:dontBroadcast)
{
    new victim = GetClientOfUserId(GetEventInt(event, "userid"));
    if( g_bSilent[victim] )
    {
        return Plugin_Handled;
    }
    return Plugin_Continue;
} 


[FatallError]

Thank you.
Just right

[FatallError]

But on the other hand is still interesting.

What are the tools to control entity life in the world except ForcePlayerSuicide (client)?

[Bacardi]

aa...
GetEntProp

PHP Code:

new health = GetEntProp(entity, Prop_Send, "m_iHealth"); 


SetEntityHealth(entity, amount)