Overview:

You live a mundane life with your uncle and life long friend, on an island with few inhabitants, secluded from the mainland of Avalon. Little do you know, an ancient evil is planning it’s return. You’ll discover new hardships, reveal mysteries, fight Succubi and other creatures, interact with your (not always) helpful companions, and seek an end to this great threat.
(Succubus Advent game has NSFW CGs leading to the main characters death and subsequent game over.)