Elias Papavassilopoulos (alias "CaveMan") was a notable member of the early Doom community, particularly through participation in Usenet in 1993. He was the first person to decipher the encryption used on the Doom cheat codes in the game's executable file, publishing the results as a mostly complete list of the cheats to the comp.sys.ibm.pc.games.action group on December 15, 1993. He did this by using a 32-bit executable disassembler for MS-DOS which he created himself, using it to locate and reverse engineer the cht_checkCheat routine in the DOOM.EXE executable file. Managing to do this so quickly impressed id Software programmer Dave Taylor, who was responsible for implementing the cheat codes and their method of encryption, and Dave sent Elias a t-shirt he was wearing at the time in exchange for an explanation of how it was accomplished.
Elias later participated in creating The Unholy Trinity, a significant early PWAD recreating the campus of Trinity College, Cambridge, which was named one of the Top 100 WADs of All Time by Doomworld.
- Papavassilopoulos, Elias (15 December 1993). "DOOM cheat codes." comp.sys.ibm.pc.games.action. Retrieved 31 October 2019.
- Papavassilopoulos, Elias (29 October 2019). "Impressive bit of DOOM arcana archeology. After publishing the cheats David Taylor reached out and promised me 'the tee off his back' if I described how I managed to get the cheat codes. I obliged and he made good on his promise." Twitter. Retrieved 31 October 2019.