Thanks for all the replies
True, such a game could play off of a lot of LE's strengths. As well as the lighting, if physics were used well for the gameplay, or indeed shaders were used cleverly, then the game could have a lot of unique aspects to it. The flashlight isn't a bad idea at all.
The hardware requirement is obviously of key importantance if a game like this were to get released, especially if it were capable of being run by an engine of lesser power or hardware needs. I suppose a survey would have to be considered at some point if this project intended to be released, whether for free or otherwise. It all depends really on whether more hardcore gamers would consider playing, if the game showed impressive graphics and other features etc. which are also commonly seen in 3D games, and also whether a number of casual 2D players also tend to have good computers as well. It's all a complicated question, quite a lot of things I need to consider. LE may be a worthy engine, but it depends on certain factors and how the game ends up.
But then, as Pixel said, I could spend so long on this in theory that by the time it is finished there will be many more players with the needed hardware, hehe