The monthly updates you see are the developer just sharing their progress on the "sequel" to the latest release. The most recent version is the one in the first post in the first page, version 1.8, which contains Episode 0 (The Dealer) and Episode 1 (Alice & Herba).
The sequel will be Episode 2, and if I'm remembering correctly it'll feature around 8 characters give or take. There's no current ETA for the release date, and it seems like they've only just started building up the gameplay systems and hentai scenes. The settings and character models are almost complete, I think.