What engine to use?

Hi,
I'm not a complete newbie to game development, I've already got some experience with Flash and Unity 3D. But, for the next game that I'd like to create, I need an engine/library that enables me to do the following:
- Create Doom-like graphics (like raycasting) BUT with rotation over the X-axis and mouse input. So, basically, low res textures and low res for the game itself too.
- Open a folder/file or create a folder/(text) file on closing.
3D development can be very tricky in Flash, but I don't think Unity will let me manipulate files, or get me the "Doom-effect". Which engine or library do you think is best?

Thanks,
Arne Gevaert

Best Search Engine is Google.....

The Unreal Development Kit is what we use for our game, Dark Storm.

The team certainly seems to like it.

You can see some of the stuff we've done with it at adarkstormiscoming.com

What your asking for definitely sounds like a Unreal Development Kit kinda engine.

Easy as hell to use and great results.