Getting the SDK

First what you must get is the main game engine. You can download all binaries packed with playable and ready to run FOnline game with fully completed scripts. It will let you to know how it's working, how it's built, how looks the file structure on client and server side.

Which SDK should you choose?

There's few of them. The newest revision of engine doesn't include any type of content, still under development and you'll be able to get the technical support from the main engine developer - cvet. You can download it directly from GitHub repository by f.ex. TortoiseSVN - a tool for repositories. Link to repository: https://github.com/cvet/fonline

Another type of SDK is old and includes simple solutions in game - The Life After. You can find there an examples of World Map known from Fallout 2 game with already existing locations and simple features, dialogs, prototypes, scripts and tools used for creating it. It's partially supported by FOnline Community. You can download it directly from GitHub repository by f.ex. TortoiseSVN - a tool for repositories. Link to repository: https://github.com/worldremaker/FOnline-SDK

More advanced SDK with examples - FOnline: 2238 includes the world known from Fallout and Fallout 2 games which is merged to the one big game's world with all locations featured there. This game includes finished PvP features (most known: Town Control, Faction Mod) but it's on 391 of engine revision and it's not supported anymore by authors. You can get it directly from GitHub repository by f.ex. TortoiseSVN. Link: https://github.com/rotators/fo2238

It's not all. There're SDKs based on FOnline: 2238:

• FOnline: Reloaded, both first seasons made on 391 of engine revision. During the run of these the authors made there some rebalances in whole game (probably the most succeed balanced FOnline game released as SDK). It's partially supported by authors and FOnline Community.
• The 2nd season of FOnline: Aftertimes - built on SDK taken from 2nd season of FOnline: Reloaded. Whole project was upgraded to 412 of engine revision and later modified it by fixes and adding of new functions. This SDK includes few more of game features (most known: Dynamic Mobs, Base Control) and some part of Fallout of Nevada's content (few reworked locations). It's partially supported by author.

Links:
FOnline: Reloaded season 1 (server and tools): http://files.fonline-aftertimes.net/other_sources/FOnlineReloaded1stSeasonPart1.zip
FOnline: Reloaded season 1 (client): http://files.fonline-aftertimes.net/other_sources/FOnlineReloaded1stSeasonPart2.zip
FOnline: Reloaded season 2 (server and tools): http://files.fonline-aftertimes.net/other_sources/FOnlineReloaded2ndSeasonPart1.zip
FOnline: Reloaded season 2 (client): http://files.fonline-aftertimes.net/other_sources/FOnlineReloaded2ndSeasonPart2.zip
FOnline: Aftertimes season 2 (server and tools): http://files.fonline-aftertimes.net/official_releases/fonline_aftertimes_s2_server_tools.zip
FOnline: Aftertimes season 2 (client and mapper): http://files.fonline-aftertimes.net/official_releases/fonline_aftertimes_s2_client_mapper_full.zip

The FOnline: Reloaded Team has created the modification of the FOnline Engine called FOClassic. It's based on 412 of engine revision and it's partially supported by them. They're using it currently to run the 3rd season of FOnline: Reloaded. You can get the source code directly from GitHub repository by f.ex. TortoiseSVN. Link: https://github.com/rotators/foclassic