There's this manga that I read a while ago, and it's about a guy who works in this company that develops action-based games. His co-workers are all very rude to him, except for this lady who is super friendly to him. (Inin a professional way). I think he's the main developer or he has a major role in the game they are making. The company is putting everything in this game and they are putting a lot of pressure on him.
Somehow, the game becomes real (I don't remember how) and monsters show up in the office they all work in. He gets them all to safety through his knowledge of what happens in the game. He then finds a room with an easter egg in it that he made. (It's a skeleton version of him sitting at a desk.) That's all I remember for the beginning,beginning; I do remember that later on they run into some guy who used to work for the company and he helps them out.