Killspree is a small, frantic, single player map made by Sonik.
It's one map split over two levels. Killing the enemies as you go, make your way to the first switch to activate the elevator, then once on the upper level kill a lot more enemies to get to the switch to complete the map. Your only weapons are the pistol and the tommy gun.
The level only uses a few textures and it includes a custom skin for the thug. Its a tough level but once you work out how to use the level to your advantage (hide and reload, shoot from corners etc) you should be able to complete it in ten to fifteen minutes :)
Just unzip the files to your Kingpin folder and they will be placed in the correct locations.
You can start the map by opening the console, and typing "map vr_killspree.
But I recommend making a desktop shortcut for Kingpin and add the following :-
+set developer 1 + skill 1 +map vr_killspree
(skill can be 0 = easy, 1 = normal, 2 = hard)