Somnium is a yume nikki fangame by M-256 (Isasapiens) (DeviantArt Tumblr Youtube), who also created Me .
"Thomas here is Me's neighbour. Unlike most people, Thomas frequently daydreams onto his bed, about various things, varying from cakes to steamwork-like places, passing through digital glitches and rooms.
Unlike many Yume Nikki fangames, in Somnium you do NOT choose where you go, much like Lsd: dream emulator. To wake up, you have to get “memories”. They’re often a bit different from the dream part where you are.
There are dream layers. Those are usually different places than the original dream. Being 4 on total, they are usually acessible through interacting or passing through certain objects."
(Taken from Somnium's page from Isasapien's Tumblr)
Gameplay
The game has no effects, but instead you obtain memories. You can save anywhere, even in the middle of a daydream via the menu.
The game isn't as dialogue heavy as games such as The Looking Glass , but Thomas does comment on things from time to time. The game is similar to N'Oubliez Jamais, in that you collect/search for memories, but with the more traditional exploration mechanic.
Each time you get a memory, you are warped back to reality with the memory in your menu. Some memories give you the option to take the memory, or to go deeper into the current "layer" of the daydream.
External Links/Download
Download Version Beta Here
Updates for Somnium and Isasapien's Other Works Here