My first forum was a Pokemon rom hacking community and it was hosted on Forumotion. I had no clue what I was doing at the time, let alone I had a hard time understanding how to set up permissions in phpBB lol. This was also during a time where we only had tools to mod the Pokemon games, no disassemblies. I also wasn't too experienced in ROM hacking in general either, both with Sonic and Pokemon so I am not sure why I picked that to be the niche of my first forum. :V
