You start out in the center left part of the city. Get used to how this part looks, because you'll return her every single time you die and you'll have to inch your way back to where you were.
The gun has eight levels of power. For the first two, you have the standard yellow pellet. Upgrading it makes it go faster and further, but it's still not very powerful. Next, you'll get the orange crescents. These have two levels of power and distance, but they can get caught on the walls unless you're standing in the right area.
Ditto for the next two, which are black balls that circle around as they go forward. Unlike the crescents, they're even worse with running straight into walls.
The final weapon is a bunch of pink triangles. They cover a wide area and they travel in a double-helix pattern that's more reliable than all the other weapons, so max out your gun power as soon as possible. You can power that weapon up just one more time before you're finally maxed out, and this will turn the double helix shot into an even better triple shot that doesn't arc around at all.
You can go to the inventory screen to see what level your gun is at any given time. Same for your whip later in the game, as you'll soon find out.
In this game, you have two hits before you die. You can find two extra hits to add to your maximum health, but that's as far as the game will allow you to upgrade it. Still, the health upgrades are a big help.
The frogs jump toward you, and sometimes they can be the death of you. They can also attack you with their tongues, which have a bit of range to them. If your weapon keeps hitting the walls, either use the whip (which you won't be able to do yet) or either reposition yourself or run away. Hugging the east wall in a narrow vertical corridor or the south wall in a narrow horizontal corridor usually helps. Also, try advancing slowly so enemies like the frogs that slowly but surely jump forward will go down. That's nice, especially when the respawn rate for monsters is so instantaneous and unnecessary that it's brutal at times.
The purple things on the ground that look like grapes can be destroyed easily. Just don't be stupid enough to walk into them. They're really good for filling up on money, light bulbs, keys and weapon upgrades.
The orange heads that float in place won't bother you until you shoot them. When you shot them, flies come out. You'll have to take out both the heads and the flies to move on.
For the houses north of where you begin, Pugsley (whose name is spelled wrong) gives you TNT, while Wednesday gives you Vice Grips. Don't even bother re-entering to get more, as you automatically get the maximum you can carry for each weapon when you get them from a house.
The staircases that lead down lead to the sewers, which you'll be entering a lot. We'll be entering from the staircase just east of the house where Pugsley gives you the TNT. Use a Light Bulb to illuminate the sewers, then equip TNT in case you need to get past a slime. The slimes multiply when you shoot them, but either shooting really, really fast or using a TNT will take care of that. (At least the slimes leave a lot of pick-ups you can use).
The heads here will now travel along the ground. You'll have to shoot them down this time, even though they leave larvae that crawl around on the ground and turn into flies after a few seconds. If anything is right in front of your gun, it's going to get hit.
The rats just hug the walls and go straight in one direction until they hit a wall, before they change direction again. They're pretty easy to take out.
Use the item button to go up the ladder, and you'll finally be aboveground again. You'll now be north of the un-crossable pit just north of the start.
The pink frogs spit three fireballs, one straight and two diagonally. The green ones will lash their tongues forward. The blue frogs and the red frogs will just lap towards you.
Go to the house in this area so Thing can give you Potions. Get as many as you can, since these will fully replenish your health, unlike the Hot Dog Stands.
The tall grey building in this area is your first first-person-shooter style segment. Of course, you won't be shooting anything in these section because there's nothing in them to hurt you. That's good.
Anyway, there's not much to this building...except. Except if you go forward, turn left, go forward, then turn left again at the first junction you see, you'll reach a dead end. Go forward at this dead end and you'll get your first health upgrade. Yay! Now you can get out of there. Don't believe me?
Use this map from ReyVGM. You're welcome.
The black monsters that look like a cross between a flea and a daddy longlegs will jump whenever you shoot at them. Just keep plugging away as they jump while moving back and forth and you'll eventually kill them.
The house north of the tall grey building in this area has Thing in it (how does he go between the two houses so fast?), and in this house he'll give you Invisible Potions. These will turn Fester invincible for a short time. Not invisible. Invincible.
You're finished here, so go back east and then turn south to hit the sewers up again. Follow the path, and enjoy the freedom of the most powerful gun power-up in the game. The frogs will go down in record time compared to the weaker gun shots.
When you reach the staircase at the end, you'll be west of the house where Thing gives you the Potions. Enter the house and
use this map by ReyVGM to get around. At the end, you'll fight a boss.
Whenever you enter a boss room, you'll get an invincibility flash. Consider this your few-seconds-long head start to align yourself properly and shoot at the boss without impunity. Anyway, this guy will attack with his extending arms, and they have some range. He always attacks left, right, right, both with his arms, then he moves around until he can immediately hit you with the left arm before repeating the sequence. Just bait him into attacking and stay on the move, and you'll do fine against him.
When you beat the boss, you'll be in an alcove next to the upper-right corner of the building. In it will be another sewer entrance.
When you check your inventory, you'll notice there is a white rectangle on the left side of the Clue window on the upper-left. When you get all the clues, you'll find out where Gomez is.
Items
All items except for Light Bulb, Keys and Money will replenish after you beat a boss.
Money: Equip and use them at Hot Dog Stands to refill a unit of health, at five Money units for each one.
Gun Upgrades: Blue ones power-up your gun, while pink ones downgrade.
Whip Upgrades: These work the same way as the Gun Upgrades, they just say "Whip" instead of "Gun." You won't be able to make use of these until you get the whip later in the game.
Light Bulbs: These light your way through the sewers. Equip one and you'll have light until you go back aboveground.
Keys: Used to open doors aboveground. Enter the locked houses to get more power-ups.
TNT: Equip them, then lay one on the ground and wait for it to explode. Anything near it will be taken out.
Vice Grips: Some enemies will slow down Fester considerably with their attacks. When that happens, equip and use a Vice Grip. You'll be at regular speed in no time!
Potions: These will fully replenish your health when you use one.
Invisible Potions: Use these to temporarily turn Fester invincible. Not "invisible." Invincible.
