Bolt Action, using plaster blocks made from molds from HirstArts.
It could also be used in any 28mm wargame, including Warhammer 40k, Warhammer Fantasy or Kings of War.
The first thing I did was cut out a piece of 3/8" thick MDF to the required dimensions, then sanded down the edges to smooth them a bit. I had some extra dental stone left over from a previous project, so I made a few molds of that, but I did the majority of the model using Plaster of Paris. Plaster of Paris is not a very durable material, but it served for this. We'll see how it holds up to actual gaming.
The molds I used are HirstArts molds #40, #41, #45, #53, #54, #60, #202, #210, and #230.
I drew the basic layout of the floorplan directly onto the MDF, and then started gluing pieces in.