Overall tips 1- When an enemy intents to grab you, inmediately shoot everyone around them, since the enemy has super armor and you will waste your time shooting it. 2- Try to launch a grenade at big enemy groups (Specially the ones coming out of fences or tight corridors). When a big group of zombies tries grabbing you (you will see some sort of VS meter) launch a grenade immediately after winning it. 3- Allowing a boss to do one of their attacks wastes a lot of time, use grenades only if you know you can't properly fight the given pattern (with some exceptions).

Chapter 1 1-Certain scenes in chapter one can be skipped if no Zombie is close to you for a couple of seconds, using grenades at the right moment can make a nice skip out of it. Some examples are the section where two doors open and you can choose to destroy the switch or right before entering the final hallway 2-Don't destroy the door switch 3-Use the left path, since it'll be way easier to get two grenade refills. Besides, there are less enemies. 3-When fighting Justice, you don't really need to use grenades against him since they don't save that many seconds. Use them only if you doubt of your skill. Also, use every chance you find for doing cheap damage to his attack bar.

Chapter 2 1-Push the door to avoid wasting time 2-Unlike I do, it's better to select the left path: the other path is full of enemies standing up with I-frames...they can waste 15 seconds just standing up. The left path has more enemies, but you can Grenade skip the bigger groups. 3-In the first appearance of leeches, try shooting at the vent to prevent more of them coming instead of focusing in the ones attacking you, you will get hit, but for good reasons 3-In the room full of enemies and a yellow barrel (the one where a zombie grabs your leg) don't shoot immediately the barrel, wait 2-3 seconds so more zombies gather around it. With a bit of luck, you may even clear the room before that scripted zombie stands up 4-Shoot yellow barrels as fast as you can elsewhere 5-Shoot the fat zombie holding the door, but don't shoot the padlock in the area with leeches 6-Shoot the gas tank of the flamethrower zombies to dispatch both of them at the same time. 7-Right before the boss, shoot the thingie holding the construction platform 8-For the boss, the only potential skip is to launch a grenade when it spawns little spiders. You can do some cheap damage when its crawling the platform up, and watch the red reticle to know how much can you shoot them before getting all tied up (it's way later than it seems)

Chapter 3 1-Let yourself be dragged to the bonus room, you can grenade skip the biggest encounters of that route 2-Select the left path, it has way less enemies, and the grenade skips are not that worth it 3-Forget about getting a headshot on the axe zombies, aim for the legs or body as you spot them

Chapter 4 1-Shoot the zombie holding the door and push the button 2-Try killing the flying zombies that stay still instead of the one trying to attack you 3-Watch the yellow barrels when you fight Temperance at the tower, they will skip a lot of enemies

Chapter 5 1- Shoot the policeman when he grabs your car 2-Watch the car's collision box when you try launching grenades 3-Fight the car when they try to push you off the road

Chapter 6 1-The big enemies' weakspot is the chest 2- You won't be able to shoot the tiny enemies until they launch their blades 3- In regards to the boss fight, try hitting his chest when you think you cannot counter his attack pattern. He will keep receiving damage. Fighting his attacks only causes him to be a bit stunned. The best chance to do this is when he makes that double freezing floor wave. During the Ice Axe attack, you cannot use this tactic. 4-During phase 2 of this boss, the same can be applied when he makes dragon patterns, shooting his chest is even more effective this time, as fighting the attacks doesn't really stun him that much. 5- Some guy at gamefaqs says that you can launch a grenade at him while he ducks during the final attack patterns (the one he spams a lot) and maybe potentially skip half of the fight. I've tried doing it, but my tries say otherwise. If you manage to do it for yourselves, just tell me.