Barrels O' Fun is the first secret level of World 4, The Demon Realm. Modeled after the level of the same name from Doom 2, Barrels O' Fun is packed to the gills with explosive Doom barrels, which make up the majority of the level. These barrels explode when hit with a projectile or shell, and are often arranged in long rows, allowing for explosive chain reactions should one detonate. Also adding to the danger is the fact that these barrels are often the only "solid ground" between you and a vat of deadly acid - should the explosions not kill you, the acid will most definitely finish the job.