Do you remember when you first discovered glitches in Pokémon?

I remember when I did. Summer, 1999, at Kingswood Summer Club. Pokémon Red and Blue was released the previous year, which I guess would make me eight or nine. The Pokémon craze was in full swing over here in the UK — every day, I packed up my Pikachu-yellow Gameboy Colour with Pokémon Red permanently slotted into its top. My friends and I would get together with our link cables for epic trading and battling sessions that lasted for the whole day, or until our parents came to pick us up.

Around mid-summer, our 'group' was starting to feel like we'd seen it all and done it all. Sure, I didn't think we’d ever caught 'em all — back then, it seemed like an impossibility. We had grinded to level 100, eliminated the Elite 4 more times than we could remember. The game was starting to lose its draw, and there were still four long weeks of summer left. Then, we saw Missingno.

I remember the first kid I knew to have him; he told us that his brother showed him how to catch this super rare, super awesome Pokémon. We gathered round as he revealed that Pokémon to us — that magical, distorted, reverse 'L' shape that held the key to infinite Rare Candies. We were all instantly in love and dying to get one of these rare Pokémons for ourselves, so he passed on the secret and showed us how.

Within the next few days, our little group was hooked on glitches. We scoured magazines for the latest bugs and tricks — we visited Glitch City, battled all kinds of high level Pokémon off the coast of Cinnabar; we even caught Mew.

But there was one glitch which I've never been able to find record of since. Funnily enough, I can't remember the details of how to pull it off, but I remember the outcome — Glitchlett. The technique for finding this little guy followed the pattern of a lot of the tedious Pokémon encounter bugs in Red and Blue — talk to this dude, fly to this place; it might have had something to do with Celadon, I'm not sure really.

Glitchlett was just as you'd expect — a glitched-up Diglett. The sprite was mostly intact, but the face was distorted, Missingno.-style. There were a few distorted lines through it, like scan lines, and the cry was a little weird too, although I can't put my finger on what it was. His level was never visible, but we guessed it must have been over 100, as we could hardly put a mark on him while trying to catch him. Most of us resorted to one of out many cloned Masterballs.

We nicknamed him Glitchlett, and that night we were eagerly trying out what his guy could do.

The next day, we all met up to compare results; by this point we all considered ourselves Pokémon glitch experts. Experiences with Glitchlett were varied — one guy claimed it messed up his game so bad he couldn't play anymore and had had to reset. Others said they tried to battle with Glitchlett only to find the game crashed every time they tried. I had the most luck in battles with the new glitch Pokémon. His only move was DIG, and he couldn't learn any HMs or TMs, even those you'd expect a Diglett to be able to learn. Against Wild Pokémon, Glitchlett was a powerhouse — he never lost PP, and together we'd OHKO'd every Pokémon we came across.

But the attack itself was... odd. It took two turns as usual, but after the first turn he'd be hit with some kind of self-damaging recoil. There was no explanation other than "Diglett was hurt!" and that strange cry, but it never made much of a mark on him. Glitchlett's HP was higher than anything I'd ever seen, and because it took only one DIG to destroy any wild Pokémon, it was never much of a problem. I laid waste to my friend's teams during linked battles, and he soloed the Elite 4.

I remember when things got even stranger. I was levelling a team using the Exp. All — destroying wild Pokémon with Glitchlett seemed the obvious choice and I'd maxed many Pokémon this way in the past. I'd woken up early that morning to level especially, and had spent all day KO'ing wild Pokémon. At that moment I was under my bed covers with my trusty Gameboy Colour light — Mum would go mad if she knew I wasn't asleep at this time. Everything was going to plan and my new team was levelling up beautifully. I must have been concentrating pretty hard, because it was too late when I noticed how low Glitchlett's health had become. I selected DIG for the final time and watched him begin to descend into the ground... as expected, I received the message "Diglett was hurt!". I heard that piercing cry, louder then before, and my stomach turned as I watched his health bar slide towards zero. The bar doubled back on itself, and seemed to empty four or five times before Glitchlett repeated his dying cry — now a horrible noise.

"Diglett was killed! Do you want to use the next Pokémon?"

I know it's cliché in this kind of stories, but I remembered that vividly. I selected NO — my other team members wouldn't have made a mark on this enemy Pokémon anyway. I was warped to the over world and found myself back in the Unknown Dungeon. Opening my Pokémon menu confirmed what I'd seen before — my beloved Glitchlett at the top of the party, health reduced to zero. I selected him, I'm not sure what good I thought it might have done... and noticed that something was different. Maybe it was there before, but I think I would have noticed that DIG was now selectable outside of battle.

I thought for a moment. Maybe it was the atmosphere, but this move was suddenly chilling me. Glitchlett had never been damaged by any Wild Pokémon, only by this move. It wasn't even as though he's hurt himself in confusion or with recoil... whatever had hurt and ultimately "killed" him had been underground all along, waiting, sapping Glitchlett's life each time I sent him to attack. His death-cry echoed in my ears as I realised what I'd done. My thumb hovered over the A button, my brain willing myself to DIG and get out of the cave, but my stomach felt sick. What was down there anyway?

I was stuck with no choice. The exit was too far away, my remaining Pokémon would be destroyed if I tried to get there. With a lump in my throat, I dug, and my sprite began spinning into the earth and the screen went black.

I wasn't surprised when I realised where I was. Not the entrance to the cave, or even the nearest Pokémon Center, but a glitched-out cave that I now realise was some kind of bugged version of Diglett's Cave. I checked my Pokémon, and saw Glitchlett's health had been restored. He was now my only Pokémon, the other five members of my team missing entirely. I chose DIG again. Oak scolded me — apparently this wasn't the time to use that.

With no means of escape I set off looking for the exit. My sprite moved slowly, more of a crawl than a walk; as I moved, the cave's walls bugged out — turning red, flexing and swelling in and out like the lungs of a monster. Slowly, music began to play — high-pitched and distorted and horrible. It was quiet at first, but grew louder with every step. As it played something became familiar — a familiar tune beneath the whirring, bugged notes. Without thinking I began to mouth the words to the music.

"Diglett-dig, Diglett-dig, Trio Trio Trio... Diglett-dig, Diglett-dig, Trio Trio Trio..."

Then, I encountered a Pokémon.

"A Wild Dugtrio Appeared!"

As the distorted battle music began, the level 225 Dugtrio appeared before my eyes. The cry was an awful, warped scream that seemed to become a gnashing crunch before stopping entirely. Dugtrio's sprite, like Glitchlett, was deformed — Dugtrio's three faces with hollow eyes, twisted into pixelated howls that looked somehow painful. The bottom of the sprite was unrecognisable — it looked as though six deformed, clawed arms were rising from the dirt around Dugtrio's body. My only Pokémon was released and Glitchlett's back sprite appeared before me. His cry played again, quiet and seemingly a lot weaker.

I was just a bystander now as the game took control, selecting an attack from the menu. Of course, DIG was the only option. My hands were sweaty as I gripped the Gameboy tight; my breath was hot on the screen. Dugtrio went first.

"Dugtrio used Scratch!"

It hit six times, each tear triggering the pitiful cry from my glitch Pokémon. Glitchlett was left with a sliver of health as he retaliated with an attack of his own.

"Diglett used Struggle!"

It hardly made a mark, as expected, but it was strange how DIG had never lost PP before.

As previous, the game selected the next move. As ATTACK was chosen, I noticed that Glitchlett suddenly had no moves. Two words appeared where the first two attacks should have been.

NO HOPE.

Dugtrio's cry echoed again as it launched an assault of scratches with its deadly, horrible arms. Glitchlett was killed after the first strike.

"Diglett is Dead. Do you want to continue?"

I didn't really understand the question, but that didn't matter. NO was selected for me, and the battle faded away. Back on the over world, the walls swelled and glitched before my eyes and the maddening music began again. I inspected Glitchlett. His sprite had changed now, although his face was never visible, like Dugtrio's it seemed to be formed into a pixelated scream. Dark brown streaks cut through the sprite — they looked like claw marks, or blood.

I pressed on. I don't know what I was thinking at that stage — just that this tiny Pokémon had infected my game in a much bigger way than expected. Glitch Pokémon seemed kind of wrong to me then, as though it was something I ought not to have been massing with — something we didn't understand or couldn't control.

With no Pokémon left, I was surprised to find that I didn't "black out" or warp to a Pokémon Center. The game just continued as usual. It was only a few steps before the Pokémon encounter theme played and the screen turned black.

"A Wild Dugtrio Appeared!"

This Pokémon sprite was different to the last — almost completely disfigured. The cry seemed as though it wouldn't end, screaming and wailing as a pixelated monster appeared on screen. Through the glitches and cut pixels I could make out the hollow sockets of eight eyes, eight terrible clawed hands and a gaping mouth.

With no Pokémon left, my trainer's back sprite faced the glitch head-on.

Before my eyes, the screen faded as my Gameboy's batteries cut out. Whatever had just happened gripped me with fear. That night I didn't sleep. I even took the game out of the now dead Gameboy, although I'm not sure what that would have done.

Days later I started that game up. I'd not saved during what had happened, so I was returned to my last save point. Glitchlett was at the head of my party, DIG his only move.

I thought for a moment, before abandoning that game forever and starting anew, but I'll never forget how it all started and how it all happened. Like something out of a horror movie that keeps on repeating and repeating over and over and over whenever I saw that glitch head-on. But everybody has to move on and I can't seem to forgot the whole thing like it never happened. Like digging into my skin and controlling me and my actions. But it's all in my head. I know I must have been hallucinating this whole thing, but when I see that cartridge, all the horrors I fear are still in there, waiting for it to come out and scare me forever in my head for eternity to come.