This means, that we can play bf2142 base game or even "FIRSTSTRIKE mod" via Tunngle, Hamachi or via server's public IP 

HOW-TO is here http://forums.fsmod.com/viewtopic.php?id=11130

And so, the Battlefield 2142 game can currently be played local LAN only:
a) via DETHKLOK CLAN's "NEW STATS SERVER EXE" patch;
b) or, If you have game patched up to 1.25 patch only.

If you want to try a) option, please follow this topic: http://forums.fsmod.com/viewtopic.php?id=11130
If you want to play local LAN via 1.25 patched game (e.g. with your friends at your home's network), read the following...

...HOW-TO:
1) You have to have:
i) Old physical DVD installation media (can be old, second hand, you don't need unused key);
ii) warez DVD clone iso release (e.g. google for "rzr-2142.iso" torrent, size=3,5 GB).

2) After installing base game from DVD or ISO file, you must pach you game with this patch BF2142_Update_1.25.exe (size=302 MB)
LINK to get all the patches, e.g. here:  http://www.bf-games.net/downloads/categ … tches.html

3) Create offline account like this http://forums.fsmod.com/viewtopic.php?id=11120

4) That's it. Now you will be able to play SP or local LAN with your patch 1.25 game.

5) NOTE: And again, If you want to play local LAN with patch 1.51 version, you must use DETHKLOK CLAN's "NEW STATS SERVER EXE" patch.