Hello.
Yes, this is a demo. The full version is currently only available on Steam.
However, next week I plan to update the game to version 1.5. The graphics of the game will be improved.
Starting from 1.5, the demo will contain all game content, with the exception of the Green Furies DLC.
Update Details:
https://kirillkrm.livejournal.com/309883.html
After the update, I will post a new version of the game on itсh. I planned to sell Green Furies only on Steam. However, if the itch audience likes the free version, maybe I'll change my mind.