It's been ages since I've read it, but the only part I can seem to remember is that the protagonist kills a tonne of people inside this tower and then blocks the stairs to the next level and kills anyone who tries to get past him. It may have been a survival type novel with game elements, where the participants have to complete challenges to get rewards. I understand it's a little vague, but any help would be appreciated!
yep its King of the Battlefield, in the tutorial section, in the slaughter tower where only people who have killed someone can enter
<= only remembers that it's in a tower full of crazy killers... i see.. King of the Battlefield huh.. *nods nods*