Well, I just found some very cool things, codes that work just if you playing a game, and give very cool things, like bigger letter size, different colour of lettets, etc...
Example:
if you say:
<font=Arial 48> insert text here
in a game, then your text will appear in enourmous letters,

This are all the codes I found.
<font=Arial 48> insert text here. and you will have enourmous letters in-game.
<font=MainMenuButtons
18> Big text, though not giant.
<icon=(20)(ui\hp_cp\hp_cp_rec_gold)> An icon that shows an image of gold
<icon=(20)(ui\command\generate_food_off)> An icon that shows an image of food
<icon=(20)(ui\command\generate_wood_off)> An icon that shows an image of wood
<icon=(20)(ui\command\generate_gold_off)> An icon that shows an image of coin.
<color=1,0,1> pink
<color=2,2,0> yellow
<color=1> red
<color=0> black
<color=0,0,1,6> blue
<color=0,9> green
<color=0,8,7> light blue
<color=1,0.8,0.2> orange
<color=0.8,0.1,0>-<color=0.8,0.9,0>
the color will be changing from this to this.
<color=0.8,6.4> green-yellow
This Just works in-game, if you put /w (insert name of user you want to whisper here) (insert text here)
You can whisper to anyone (just works if you are playing in-game).
Example:
Just say /w greatapollo19 hello
Greatapollo19 will recieve a whisper of hello, of you when you are playing in game.
The problem is that the guy you whispered, cant contact you, or at least I never heard of anything that allows him to reply what you said.
P.S.
If you find a cool code like one of those that I mentioned previously, please mention it here.