Through the Trap Door/Walkthrough

You shall first have to connect your Sinclair ZX Spectrum, Amstrad CPC or Commodore 64 and cassette recorder to your television, then switch all three of them on; you will then have to place the cassette of Piranha's 1987 action game, Through the Trap Door into the cassette recorder, rewind it (unless it is your first time playing it), type LOAD "" (without leaving a space between the quotation marks) and press Enter to load the program into the console; while the game's rendition of that show's theme song is being heard, you can press K to redefine the default keys to any combination you want, or J to switch input to a Kempston joystick (if one is connected). You'll then have to press S to start the game - and a map for it was published in Kamikaze Guide magazine in February 1988, while a solution was published in Your Sinclair Smash Tips magazine in August of that same year (but, as mentioned on the game's main page, the show had been succeeded by the rather inferior cell-animated Stoppitt and Tidyup at the time the game had got released).

Area 1
At the start of the game, Berk, Drutt and Boni shall all be in the room at the top of the above map, as the trap door opens, a skeletal and headless bat-like monster flies out of it, comes up under Boni as he starts saying "HELP!", then flies back down the trap door as it closes again; when it opens again, you (as Berk, indicated by the sixteen small blue monsters at the bottom of the screen) shall have to fall down it through the shaft to the room below it (Drutt shall most likely also do this by himself). Once they have both landed, you will have to switch to Drutt (the colour of the sixteen small monsters at the bottom of the screen will change to yellow to indicate it), start bouncing towards the left side of the room while watching out for the enormous green vampire bat, and bounce in place below the key (he shall bounce higher each time he lands, and eventually hit his head on the key to make it fall to the ground) - and you shall now have to switch back to Berk, start walking towards the same side of the room (while watching out for the three red spiders and the enormous green vampire bat), pick up the key and retrace your steps back to the centre of the room. You will then have to switch back to Drutt, start bouncing to the right towards the edge of the pit upon the right side of the room, bounce in place until Drutt reaches the ceiling, then bounce to the right over the pit, bounce in place below the candy (he will again bounce higher each time he lands, and eventually hit his head on the candy to make it fall down to the ground), and push the candy to the left into the pit; you will then have to switch back to Berk (who is still holding the key), start walking towards the right side of the room, fall into the pit (he will drop the key when he lands), eat the candy that Drutt pushed into the pit (the screen will flash for a second) and pick up the key again. He will then grow a pair of bat-like wings and fly out of the pit over to its other side (again, dropping the key on landing) - and you will then have to pick it up again, and put it in the door (the screen will again flash for a second), then pick up Drutt and go through it.

Area 2
Once Berk (still holding Drutt) has reappeared, on the right side of this area's only room, you will have to make him put Drutt down, then switch to Drutt, bounce in place below the first mushroom and key (he shall once again bounce higher each time he lands, and eventually hit his head on the mushroom and key to make them fall to the ground), then bounce towards the left side of the room (while watching out for the falling stalactites and one-eyed green monsters, along with the yellow beaker-like monster which is firing a ball into the air from the hole in its head and catching it again), and bounce in place below the second mushroom (he shall yet again bounce higher each time he lands, and eventually hit his head upon the mushroom, to make it fall to the ground); you shall now have to switch back to Berk, eat the first mushroom (the screen will flash for a second), and start walking towards the same side of the room while watching out for the falling stalactites. However, once he reaches the four one-eyed green monsters, he will start bouncing in place like Drutt - and once he reaches the ceiling you will have to bounce to the left over each of the four one-eyed monsters along with the yellow beaker-like one. You will now have to eat the second mushroom (the screen will again flash for a second), pick up the yellow beaker-like monster, and put it down next to that fourth green one-eyed one (when the former fires its ball into the air, it will land on the latter and kill it, and you will have to repeat this process thrice more), pick up the key, and put it in the door (the screen shall once again flash for a second), then pick up Drutt again and go through it to the third area.

Area 3
Once Berk (still holding Drutt) has reappeared, on the right side of this area's only room, you will have to make him put Drutt down, then start walking to the right of the room's ground floor and pick up the flashing pair of eyes, switch to Drutt, and bounce in place (once he is reaching the ceiling, jump to the right to land on the room's first floor); eventually, Berk will eat the flashing pair of eyes by himself (the screen will flash for a second), fly up to the ceiling (the screen shall then flash for a second again), and fall down to the first floor as control is automatically switched back to him. You will now have to start walking to the right side of the first floor (while watching out for the enormous yellow claw that is coming down from the ceiling) and put the three electric-eel-like monsters into the three square holes upon the wall which match the colours of their light bulbs (red, yellow, and white) - and once you have done so, another flashing pair of eyes will fall down from the ceiling. Once you have picked these up, you will have to fall back down to the ground floor (Berk shall drop the eyes, when he lands); once you have picked them back up again and eaten them, the screen will once again flash for a second, and once you have picked up the weight, Berk will again grow a pair of bat-like wings, and fly over that enormous yellow mask-like monster (leaving the weight in mid-air, when he lands). You shall then have to switch back to Drutt, bounce in place under the weight (he shall, for a fifth time, bounce higher each time he lands, and eventually hit his head upon the weight to make it fall to the ground), then bounce in place under the key (he shall, for a sixth time, bounce higher each time he lands and eventually hit his head on the key to make it fall to the ground), then switch back to Berk, pick up (and eat) a third pair of flashing eyes (the screen shall yet again flash for a second, and he will become invisible!), pick up the key, retrace your steps back to that left side of the room's ground floor, while watching out for that aforementioned enormous yellow mask-like monster, put the key in the door once Berk becomes visible again, then pick up Drutt and go on through it to the fourth area - and this is where Boni is, but that skeletal bat-like monster is no longer attached to him.

Area 4
Once Berk (still holding Drutt) has reappeared on the right side of this final area's only room, you'll have to make him put Drutt down, then start walking towards the right side of the room (while watching out for the various colours of slime falling from the ceiling), and eat the red jelly bean (the screen shall flash for a second); Berk will now, again, start bouncing in place like Drutt, and once he reaches the ceiling you will have to bounce to the right over the skeletal and headless bat-like monster (that kidnapped Boni at the start of the game), along with the enormous pitchfork-wielding skeleton. You will then have to fall into the pit on the right side of the room (while watching out for the white spook, and the enormous yellow snake that is stuck in the left wall), switch to Drutt, make him fall into the pit as well and bounce in place under the key (he shall, for a seventh time, bounce higher each time he lands, and eventually hit his head on the key to make it fall to the ground) - and you shall now have to switch back to Berk, eat the cyan jelly bean (the screen will, again, flash for a second) and pick up the key as he (once again) grows a pair of bat-like wings and fly out of the pit over to its other side (dropping it on landing). You shall now have to pick up Boni from his hole in the wall (who is coloured yellow in this area), put him down, eat the second cyan jelly bean (the screen will once again flash for a second), and pick up the key again as Berk yet again grows a pair of bat-like wings and flies back over to the left side of the room (again, dropping the key on landing); once you have picked it up again, and put it in the door, you will have to repeat everything you did with Berk (as Drutt is still stuck in the pit, and the jelly beans will regenerate), only this time, you will have to pick up Boni, after eating that second cyan jelly bean. You now have to pick up the cannon in the left side of the room, and hold it under one of the various colours of slime falling from the ceiling to catch about eight droplets of it, then put it down (as it starts firing the droplets towards the enormous pitchfork-wielding skeleton) - and once one of them has hit him, he will transform into another Boni (who is correctly coloured white!). You will then have to do everything you just did twice more with Berk, only this time, you will have to pick up Drutt, after eating both cyan jelly beans; you will then have to pick up the white Boni and go through the door (and they will both fall down another shaft down to the room in which they started followed by Drutt as the text "HOME SWEET HOME" appears above them).