FOG (フォグ) is a Yume Nikki fangame made by Naylan in RPG Maker 2003 and RPG Maker MV. It is the first game in the dreamFOG (ドリームフォグ) series. The current versions are v0.0.52R (RPG Maker 2003 version for Windows) and v0.0.51M (RPG Maker MV version for Windows and browsers), released on October 6, 2016.
Though the author designed it as a traditional fangame, the game draws influence from media outside Yume Nikki, such as game franchises like Phantasmagoria, BioShock, Hexen, and Five Nights at Freddy's, as well as the music of Depeche Mode, Cabaret Voltaire, and Genesis.
From the Nexus, the dreamer can explore several different dream worlds. Within the dream world, they can collect various effects and perks, which can be equipped to raise certain stats which may affect their dreams.
FOG has included various puzzles throughout the dream world since the first release. Those puzzles are generally based on various visual and audio cues; solving them may reveal Effects and Perks.
As an RPG Maker MV game, version M of FOG supports gamepads, including the Xbox 360/Xbox One and PlayStation 3/PlayStation 4 controllers. Version R, which only supports three-button gamepads due to its nature as an RPG Maker 2003 game, came with improved gamepad support starting with an Antimicro configuration file in v0.0.51R, although it is already possible to wake up with the gamepad by using the Effects menu.
On April 1, 2017, the author announced that they would make the game easier in later versions by simplifying the maps, allowing the player to save anywhere in the dream world, and using a caution symbol (⚠️) to indicate to the player that an actual puzzle, as opposed to a red herring, is present.
The game takes place in November 1998, following the lucid dreaming exploits of Leon, Tegan, and Emory as they explore their shared but corrupted dream world after their friendship fell apart. They may find ghosts of each other, as well as recurring antagonists such as Fedoras and Shadow Creatures. Although FOG has no dialogue, Leon, Tegan, and Emory may find messages visually encoded as numbers, colors, or shapes or audial encoding such as Morse code.
Leon and Tegan share the same 12-door staircase Nexus, although they cannot enter each other's bedrooms. Emory's Nexus, however, is a three-tier chamber with 17 doors out of a planned 32.
"Become a Light Creature."
Leon becomes brighter, increasing his speed.
"Carry a bug sprayer."
Leon carries a can of bug spray that can kill certain NPCs and break certain blocks.
"Carry a flashlight."
Leon carries a flashlight. Pressing Shift turns it on, illuminating certain areas and warding off Shadow Creatures. However, it has limited battery power, the battery recharging when it is turned off.
"Become an at sign ('@')."
Leon has a red at sign (@) for a head.
"Go barefoot and change for the summer."
Tegan becomes barefoot, increasing her speed.
"Become an onion knight."
Tegan has an onion for a head, along with a sword a shield, making her able to kill certain NPCs and break certain blocks.
"Change into mouse pajamas."
Emory wears a mouse suit, increasing his speed.
On March 17, 2016, Naylan released a condensed mini-game made with RPG Maker MV, Tegan's Traverse, which allows the player to walk through the 12 main worlds with any of the three Dreamers: Tegan, Leon, and Emory.
On April 30, 2017, Naylan released a selection of assets from FOG in a set of free materials called Dream Origins, made for others to use and edit for their own games for the Dream Diary Jam on Tumblr but can be used for any purpose under either the Creative Commons Attribution 4.0 International License or the MIT License.