yeah its their own engine, in terms of graphics its not that different from Source, as in, its not the best graphics you will see on the market. and I am not intending to rip it directly from the engine, I am going to recreate most of the things from BSP, and then model props such as benches, light posts, shelves etc. I may even expand this map a bit since it seems good for 2-6 players max
also I have an idea for a remake of classic de_westwood from cs1.6 that would fit the DA:B better, might give it a try after doing the payday map
I will add you on steam or skype once I have something sorted out