Stage 1
Go to the first left you can take, in the room with the thief in it. Unequip your hood/helmet before going into his room to get your first sex scene. In the trap corridor, push/kick the rock to your right onto the track to break the circular saw, allowing you to just run through. In the room with the urns, the safe route is to jump over them, since going anywhere else will kill you with arrows from the walls. Ignore the stairs and go right to the slope, rushing down and through the door to your left to avoid the boulder. In the room with the statue you need to first kick the ominous crystal, and then pray to the statue, which will deactivate the trap guarding the stairway out of the room. With the crystal gone you can now summon your staff and kill the thief upstairs. Or you can just ignore him and run up the next flight of stairs to stage 2.
Stage 2
This stage is just a pretty straightforward maze, and the developer was so kind as to give you a map to it in the same folder that the walkthrough is in. It's really quite simple: go through the portal in the big room to enter the maze. Here, ignore literally every single thing that's not a portal showing off the maze, a dark crystal or one of those statues you prayed to in the last stage. The only enemies in the maze are lizard folk which can either be baited to attack so you can run past them, or lured into spike traps in the middle room. If you actually want a guide for it, then here you go:
Take the first left you can, ignoring the forward route (leads to a mimic death scene I think), turn left again (you can walk through the wall on the right). At the end of this corridor, turn right into the wall, it's not actually there. Go forward at the next choice immediately after the hidden door and go down the stairs, enter the portal and kick the crystal. Back in the maze, go up the stairs and turn left, then left again, and then, you guess it, left in the middle of this corridor. Enter the portal at the end to get to the statue I spoke of. Ignore it, since you can't pray to this one, and instead shoot your staff laser at the eye on the wall, opening up a hidden passage. Go into the room and jump over the boxes on the left side of the shelf, open the chest and use it until you can't use it anymore. This will unlock new outfits and a masturbation scene.
Go back to the maze and go left (right being the way you came from). Continue through this corridor until you reach a flight of stairs with notes at the bottom (taking the left turn here leads to another game over scene where you get stuck in a wall). Laser down the lizard or just run past him. Ignore the lizard dude sticking his head out of the wall (unless you want to unlock my favorite sex scene of the game), and turn right instead. Continue down this path and take a left, avoiding the spike trap and pressure plate, and jump through the portal. Laser down the lizard in here or just ignore him and run up the stairs to get to stage 3.
Stage 3
This part is all about avoiding the gravekeeper, unless you want to unlock his scenes of course. If you do, there's three of them: two for getting caught (you get tied up and fucked in one, and the other is him mummifying you, ripping out your intestines and all. Just get caught by him for both of them, with the latter having a lower probability of happening), and one for getting caught after stomping his precious eggs he has hidden in one of the sarcophagi in the rightmost room, though the egg one has him cut off your legs and pound your mutilated body out of rage until he hilariously just yeets you into the wall.
Anyway, to beat this stage you have two options: platform your way out of it (stupid difficult), or explode the gravekeeper. To preface, the scorpions do literally nothing to you, so no need to worry about them. The zombies just grab you for a little while before she shakes them off, only really dangerous if the gravekeeper is close enough to see you in the meantime. For the first option, just go to the room on the left and jump behind the bookshelf in the right corner as you come in. Interact with it three times to move it, and then I wish you good luck with not falling down and get eaten by a giant worm. To do the other option, you need to go the room on the left side, read the books, interact with the mural with the little halloween sheet ghosts, grab the now glowing cloth in the room, run over to the room on the right side (while avoiding the gravekeeper of course) and grab the charcoal in here. You might not have time to get out again before he enters the room, but you can avoid him by hiding the sarcophagus on the right (eggs in the left) and wait until he walks out again. Go back to the ghost mural and interact with it to gain a divine little buddy. Go with your new friend and talk to the big bad gravekeeper to have him get blasted to oblivion. Grab his orb, head up the stairs and finish the stage. Getting caught by the gravekeeper unlocks bandages as an outfit I believe.
Stage 4
Start off by kicking the crystal and lasering the door to open it up. Run in and get relieved that the pharaoh or whatever is still there. Head to the room on the left side to get a new outfit. Head to the room on the right side down the stairs and read the book on the table to continue (the other two items in there aren't needed). Going back up the stairs you'll find that there are now thieves in the big room where the crystal was. Go out to greet them, and then make your choice for if you want to unlock more scenes or not. Going back into the room with the pharaoh has one of them chase you and get obliterated, making them aggro. It's really damn difficult to defeat them if you do this, since you're not allowed to attack from in there, despite them not following (ghost buddies will turn on you), and going back out you'll just get ran down by the darker thief on the left. If you get tackled by either of the darker thieves you'll get one of two scenes depending on if you killed any of the others (dude dying to ghosts does not count): they fill you with coins if they're all alive, or they beat you and completely carve you up into little pieces in a really visceral scene if one or more is dead (this one is not for the faint of heart). Go past all of them and down the stairs to where the stage started and you get the third scene by getting ambushed (this one is bugged for me on version 1.01). Easiest way to kill them is to walk past them before they're aggro, stand at the top of the stairs (not in the room, and not at the bottom of the stairs) and just laser them from there. Kill all of them and then go back to where the stage started to finish it.
Stage 5
Okay, so, this one is wonky. You need to first interact with the large door blocked by a bunch of boxes, and then attack the planks covering the door. Continue forward until you find a large hole, in which you'll jump down into the pit of uncomfortable noises. Grab a mini crystal and start moving forward, ignoring any and all of the skittering scarabs and isopods, jumping over or walking around any and all green puddles. There's pretty much no way to get lost here, with there only being about two or so "wrong" paths, and neither is deadly (unless you walk into exploding mushrooms that exist in a cave for some reason).
Eventually you'll reach a large room with a bunch of sarcophagi in it, and a big... thing. Set the crystal down somewhere comfy, walk out of its light, bring forth your magic wand and blast the eye on the far wall. Go upstairs, push one of the large orbs off of their pedestals, push/kick/smack it down the stairs, laser it until it glows, and then either chase Mr. Ugly to it, or kick the orb to him. Pick your fancy magic nullifying crystal back up and head up the stairs behind where Mr. WTF was standing to find your beloved sister. Set the crystal down, laser the eyes on the pillars until she's released, pick the crystal back up, run AROUND the middle of the room up to her platform, stand at the bottom of it to trigger a cutscene.
Now when she's standing at the ready you can walk into the center of the room and fall down to the final boss. Set the crystal down in the bottom LEFT corner and get ready with your laserpointer. Either listen to their conversation, or zap the dude to end it prematurely. Sis will blast the first scarab that'll pop up, but you have to be ready to help her blast the rest. Most of the time she'll teleport to the bottom right corner, but she can sometimes decide to teleport to the bottom middle. If she ends up on top of the crystal, you're fucked. Anyway, zap some scarabs until they stop spawning, then enjoy a cutscene that ends in a hilariously badly acted villain laugh. After the cutscene is over, run and pick up the crystal again, and stand with it in front of the bad guy, stopping his magic from killing you or your sister, who's currently busy gathering energy from the people of the universe to deliver a large enough genkidama to defeat the evil Kid Buu. Smack him in the face with your staff to get the bad ending, zap him to get the good ending.
