On April 30, 2020, 色仕掛けまとめブログ (Irojikake Matome Blog) released more details on their upcoming title サキュバスデュエル (Succubus Duel), though the name may change in the future.

サキュバスデュエル Succubus Duel  hentai game prototype

They announced some of the details of the game, plus some images and a short video outlining how the game will play.

Gameplay

The game will follow a card-battle system. The system seems to have been almost completed, according to their announcement. 

The card-battle system will play in a way similar to one found in Yu-Gi-Oh!. So if you are familiar with those rules, it shouldn’t be too difficult to pick up. 

サキュバスデュエル (Succubus Duel) hentai game card battle system

Judging from the video they released, it seems players have decks with soldiers and normal fighter-looking cards. The opponent has succubus cards that, when played, have the full-sized succubus portrait appear and speak. 

After dealing enough damage, just like サキュバス戦記 (Succubus Senki), they will also attempt a last-ditch attempt to seduce you to recover. 

The current prototype appears to have been created using the Unity engine. 

Many hentai games that have been created using Unity, a lot of the time, seem to have performance/optimization issues.
However, many hentai games that used Unity were 3D. サキュバスデュエル (Succubus Duel) appears to be fully 2D, so performance should not be an issue.
The interface/menus and general usability will likely be very different to that of サキュバス戦記 (Succubus Senki), which may potentially be an issue.

Update: on May 30, they posted an update on their Ci-en page that says because the game is made in Unity, it will also function on Android.

色仕掛けまとめブログ (Irojikake Matome Blog) also announced that they had completed their Chinese translation of サキュバス戦記 (Succubus Senki). Hentai in China is a topic worthy of a separate article, if you’re interested, bookmark this site and check back in every now-and-then.

Find out more about サキュバスデュエル (Succubus Duel)

色仕掛けまとめブログ (Irojikake Matome Blog) appear to be trying to create a prototype to playtest during next month. 

Update: they have created a small demo featuring the succubus maid from their first game. The demo/prototype is only available for people who donate 100yen (per month).

While I will be updating this article, for people who can read Japanese, you can also check out their Ci-en page.