Great Invasions is a Philippe Thibaut's game developed before the creation of AGEod with another dev' team.
You can find more about it (gameplay, screenshots, strategy tips, etc.) on the official website here: http://www.great-invasions.fr/
Great Invasions is not using the AGE engine developed by AGEod and Pocus for BoA and AACW. Great invasions developer, Luca Cammisa, will answer your technical questions in the specific GI Tech support forum. Philippe Thibaut will answer your gameplay questions.
This forum has been created as AGEod has signed a contract to be allowed to distribute Great Invasions in its On-line shop. The game will be on sell in few days.
All users of the previous Great Invasions forum have been invited to join the AGEod forum and, on behalf of the AGEod crew, I give them a warm welcome!
Best regards,
Korrigan