I started at 8PM last night but forgot to announce until now...
This is my 5th year, and hopefully my second success. I'm revisiting the idea I used for my 2nd attempt (MatterSplatterRL) because the concept has stuck with me and I haven't done anything with it in 3 years. This entry will be called procedural death splatter (planning to use it as part of the procedural death jam if I can figure out how to register it there), and its written in HTML5/javascript.
The central idea is that there are lamps all across the map. any space lit by a lamp, any space that is dark does not exist. At all times you are connected to a single lamp and actions you do can increase the amount of light put out (defeating enemies, crafting etc) or decrease (taking damage). This has the effect of growing and shrinking the playable area. Also everytime a space is lit it's attributes are regenerated, meaning that if the space goes dark, any enemies, items, or even the player disappear.
I hope to include an crafting system and a decent selections of items that let you manipulate the light. For example, putting down walls to block the light, using a lens to extend the light range, etc)
