What game engine should I use?

Hi,
I’m not entirely new to game programming, I have some experience with Unity3D and Flash (FlashPunk in FlashDevelop). I know there are many other Flash Libraries out there (like AS3ISOLIB), but I’d like to know what engine or library I should use for my next game. What I’m trying to make is a first-person game (so I need 3D), but with a low resolution, a bit like a 90’s game. The tricky part, however, is that I’d want to manipulate files and folders, for example making the game close by itself, and automatically create a text file, open a folder, or open a text file/image. Is this possible in Unity? Or should I do it in another engine?

Thanks,
Arne Gevaert

Like a 90s game eh? That includes Doom, which means you might be happy with a raycaster? :D

http://bruce-lab.blogspot.ie/2009/07/ray-casting-in-flash.html

Yes, you could say it’s quite like Doom or Wolfenstein, but I would like to implement rotation along the X axis too, and mouse control (If possible, of course). Basically, the ideal option would be exactly the same graphics as the games on your website, but with mouse rotation, and rotation along the X axis.