I've checked the dev's other games and there are multiple, are these games part of a series or a standalone? Which should I start with?
There is also a remake made with unreal engine should I play that version?
So in short:
There's the main Inceton branch, which consists of:
- Lust Theory - Currently has two completed seasons and a third in development.
- Summer with Mia - Their first Ren'Py game, and is a remake of their RPG maker game, Living with Mia.
- Returning to Mia - The sequel to Summer with Mia.
- Lust Bound - Their other flagship title, and currently has its first season on hiatus while other games are completed.
- LustyVerse - A sub series that consists of shorter games. Two titles exist, Shackbang and Passion on Display. Both are completed, although Shackbang is set to get a remake at some point in the future, it's just not high on the priority list.
- Undercover with Nora - Currently also on hiatus while LT3 is completed, and is set to be worked on next.
- Unreal Lust Theory - An unreal reimagining of Lust Theory. Very, very early in development, only has one completed day in the Story Mode, not really worth playing yet, and you need a beefy computer to even run it well.
There's also the NTR branch, which consists of:
- Inside Jennifer, their first completed NTR game, and a remake of the RPG maker game, Corrupting Jennifer, which was never completed based on what I can gather.
- Limits of Sky, their second NTR game, that was unfortunately abandoned at Episode 4, after finding that the game was boring when played. I for one whole-heartedly disagree with this, but Sky was abandoned for...
- Thot on Trial, their second completed NTR game. I don't think very highly of this one, and it feels rushed. A second season is presumably coming in the future.
- Resort of Temptation, their in-development NTR game. A "what-if" story, where the characters from the Vanilla games all go to a resort and sexy fun happens in various ways.
The games are all implied to take place in the same universe, although they're only loosely connected. Characters might make cameo appearances in other games, but that's where all the connection really goes. Resort of Temptation is the only outlier in this, but its not considered canon to the other games, only to itself.
Obviously some of the games are connected, Returning to Mia is a sequel to Summer with Mia and should be played after it, and Lust Theory has three seasons that should be played in order. The only other thing here is that Resort of Temptation can be a bit confusing if you haven't played basically every other game in the Incetonverse.