Yes, the project is extremely complex, but here you can find its progress.
https://atavismonline.com/atavism/atavism-for-unreal-project
We want to make it as perfect as possible and not release any unfinished features. We are also upgrading it to the newest Atavism X.12 that should be released on Unity soon as well.
For us, it's not only 1,5 years but much more time and money. Believe me, it will be worth waiting. Also, keep in mind that we are not doing any crowdfunding campaign, and except for the Epic Mega Grant that we received at the beginning, we are financing this by ourselves.
To resume, the development sped up, and as you can see on the progress page, we are at the last milestone.