CTP2 is an old game and you will unlikely find a copy in your local software dealer's bin — but fortunately it still is and hopefully will be available in future at online shops and marketplaces. It has been greatly improved by the work of dedicated modders in the past years — some of these improvements will be integrated into CTP2 Apolyton Edition along with some improved/extended modding features.
You still need to buy the original game even if you just want to play the Apolyton Editition due to the specific license under which Activision has released the source code, but you don't need the 1.11-patch listed below with the AE. Since the original game is available for download at Good Old Games (GOG — see below), the CD-check has been removed from the Apolyton Edition in order to keep it compatible with all retail versions.
You may try to narrow down your search for a localized version of the game by selecting a language and region from the menu above.
If you can't find an appropriate offer but you do find an appropriate package of localized textfiles » here, you may just take the best offer you can get in any language and adapt the game by adding the localized texfiles yourself!
CTP2 AE Playtest Versions
The Source Code Project is still in progress. Look for the latest forum thread with a title like "Apolyton CTP2 Edition: Revision ####". In the opening post of this thread you will find the latest build attached (if it is followed by many bug reports you might better go for a less recent, more stable build — of course your own bug reports will be appreciated). Important note: Due to the terms under which Activision has released the source code you will still be required to buy the original game, though all of the files on your hard drive will be replaced by new ones. Practical Recommendation: To keep a copy of the original game, I recommend copying the original \Call To Power 2\ folder, renaming it e.g. \Call To Power AE\ and copying the Apolyton Edition playtest files into this new folder (don't forget you also need to start the game by clicking the ctp2.exe in this new folder, not in the original one — take care of your shortcuts! :-) ).