Half-Life 2: SP Citadel Arena Map

This is a well made SP map by "Dr.Shark". It is based in a part of the combine citadel, a square room with no exits looks fairly innocent but no, the combine are waiting.
Hello This is the second map i've ever released, my first being crap. First off, let me answer a couple of questions you may have "So... What's this map about?" It's inside the Citadel and it's an onslaught vs. Combines with Mp7's and Sho