Yeah, it's lame to use cheats, but I completely stuck on one map :/
How should I enter cheats on HoMM II Gold? On original HoMM II in the glorious days of DOS it had to be launched with the /nwc command line parameter, but am I doing something wrong or does'n it work with DOSBOX, does it?

Yes they do work.

The numerical codes don't need any key, window, chat whatsoever.

Just type the codes directly on World Map, with your Hero selected.
(you might have to use the top number keys instead of number pad)

hi sry but only the black dragons code work?

In case anyone is searching this and still wondering WHY the codes don't work. The resource and map exploration were disabled in GOLD. They only worked in the original release of the original HOMM2. Many cheat websites do not have this information and don't test the codes. The black dragons code works, but it really makes the game off balance.
The following codes work in GOLD and I have tested them:
Effect Code
Win scenario 911
Lose scenario 1313
Last level 1911
Display entire map 8675309

You must use the number ROW NOT the number pad, the computer recognizes the difference and the programers felt like messing with 10 key users.

GoG now offers the Windows version as an optional download. Once you install this, add the /NWC (Like this: "C:\Heroes of Might and Magic 2 (Win)\HEROES2W.EXE" /NWC) to the shortcut like you normally would and then press F4 in game to switch to windowed mode.

***COLOR ISSUE WITH X64***
Pressing F4 and running in windowed mode ALSO fixes color and resolution issues of running in x64 systems. I only have Windows 7 so I am unable to test Windows 8/8.1

They only work if you are using the numbers above the the QWERTY keyboard and not the Numerical Pad.

Numerical Pad does not work.

only the black dragons work for me too