Be forewarned, some parts of this game will require the most cryptic actions - even in the context of Yume Nikki fangames - to let you progress, but don't let that sway you from giving Yume Tagai a try! Visually it holds itself high above the masses, even in this particularly pixel-art-focused genre already filled with powerful artists, and I'd say it's worth looking into for that alone; it has its fair share of particularly memorable locales as well.

2009

Deeply unsettling in a way that few other fangames that emphasize gore can accomplish, but also one of the most polished fangames with an intense attention to detail and a uniquely haunting world; .flow certainly earned its notoriety.

This fangame is somewhat weird in the way it goes about things, and there are certain areas/effects that I don't know how to progress through... but the aesthetic and general nature of the game is as unique as its main inspirations.
I will gladly wait as long as it takes for an update.

A visual tour de force of mastery over the RPGMaker engine, providing beautiful worlds with a heavy, intricate polish wherever you go; I can say with confidence that Deep Dreams is one of the best Yume Nikki fangames i've played.
in a word, the game is approachable; even though it does involve a lot of the Yume Nikki level design/puzzles that can be off-putting, it differentiates itself from most fangames by giving you almost everything you need very early on.
There are few areas that require certain effects to move through (and few effects that have impact on the environment or open new doors for you) and you can toggle sprint speed just about any time in the game instead of needing to make a beeline to a bicycle equivalent early on, so you're heavily encouraged to go just about wherever you want directly from the beginning of the game; a very welcome contrast to games like Yume 2kki that have many barriers you'd need a niche effect to get past.
The staying power of this game is overwhelming, and I think that all enthusiasts of this sort of game should consider giving this one a shot!
(Do note that there is one potentially "epileptic/seizure-warning" event, in a small flashing lights box in a cave, but as far as I know you don't need to interact with it to do anything else in this game)

A lovely and deeply-expansive Yume Nikki fangame that can probably boast having the largest explore-able world of any out there, due to its collaborative nature; "completion" of the game (regarding getting all effects and seeing an ending locked behind it) is made far less enjoyable than other fangames as a consequence of this, and I needed to look up the locations of two or three of them. Regardless, if you can find joy in the heavy variety of styles and locales, you may very well enjoy this one; it's considered one of the greats for a good reason, I'd say.
Certain links to different areas/events requiring certain effects is particularly frustrating due to the combination massive open world and sometimes-esoteric effect hiding spots though, so keep that in mind if it takes you a while to find certain keys you need to progress, like being able to tear down wooden barricades over doorways.