Cathedral Waiting For Mary Skip: In the Cathedral level, you are intended to walk around and just do whatever until the lights dim and a corrupted statue of the Virgin Mary rises from the floor, with an eye switch that you have to press to slowly start the ambush sequence. However, you can actually press that eye button the moment you get to the Cathedral floor, THROUGH the floor. I can't describe where it is, look at other runs to see. And don't be afraid to spam the "use" key trying to find it. I sure do!
Cathedral Ambush Skip: Also in the Cathedral level, you're supposed to follow up hitting the corrupted Mary button by waiting some more, then having a mosaic painting open, killing a floating Padre Pio head, and then killing an onslaught of priests and cultists, until you have to press four eye buttons on pillars to get into the Cathedral dungeon. However, by using the bastignatore, you can jump while using the secondary attack to launch yourself to the ledge of the mosaic window. The moment it starts to open, get inside and use the primary fire to kill the Padre Pio head before it can teleport out. This will awaken all of the cultists on the floor of that secret room, which you can use the bastignatore's secondary to easily kill. Be aware that before the Padre Pio head dies, all of these cultists will be unkillable. After they are all dead, use the secondary to blast jump out of the room through the mosaic window, and get to those pillars. You can hit the eye buttons even while the pillars are dropping their stone covers, so hit as many as you can as fast as you can before it teleports you to the stairwell!
By the way, there's a crucified cyberdemon in the mosaic room as well, be sure there isn't a cultist on top of it, because every single one needs to die for the ambush sequence to end.
Minimetro door: In the level Minimetro, you will start off outside the conductor's door, with a door on your right. You can open this and skip having to fight through the enemies in front of you. However, you have about a tight-rope of width to walk on before you hit the dirt next to the minimetro, which instantly kills you, so be extremely cautious when travelling out there!
Traffic Jam Skip: During the traffic jam level, You can skip the entire level by jumping off the cliff, into the water below. However, it's not exactly the water, but the boat on the water. There's a civilian in it, and in the middle wall of the boat, there's an invisible button. Hit that button and it'll skip the whole traffic level to the outside of the minimall with all the dinosaurs.
Surfing With Your Toes: In the Beach resort level, you have a long surfing section, where you are supposed to hop from board to board, with enemies popping up on new ones. The water around you will instantly kill you if you fail to jump when a board falls. However, from the very board you start on, you can leap onto the giant wave behind you and not take die. Now you can sit back and take that arena as a shooting gallery. The only problem with this is how far away some of the enemies are, so finding a perfectly accurate gun (My favorites are the ray pistol and especially the tommy gun) is almost essential.
