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How to chat in Heroes 3.5?
1) Press the {TAB} key on your keyboard (the key is located slightly to the left of the {Q} key). After that, a cursor {_} will appear in the lower part of the Heroes window, where the amount of wood is displayed (see Fig. 1).
2) Type what you want to say there (see Fig. 2).
3) Press the Enter key. After that, your message will appear on the screen. It will be written in green letters. The cursor will disappear, and to write another message, you need to repeat steps 1-3 (see Fig. 3).
Finally, if you want to say (whisper) something to only one specific player, so that other players don't see it, use the F1, F2, F3, etc. keys instead of the {ENTER} key after typing the message in step 3.
Pressing the F1 key will send the message to the red player,
pressing F2 will send it to the blue player, F3 to the brown player, etc. (see Fig. 4).
Good luck in the game!