nostr:npub1ufmlneg8tt9jwvk6p40t02lxhmkns6zlpu4cwrvxerczdnn4syzqlgqhp4 nostr:npub1xanjytp3clslynd2hxlnxg32jzz9wafxj9g4x6k28sjgljasd8wq3qjlvy also arcade games too were very popular for this, I know NBA Jam had a lot of crazy hidden characters depending on the port and the NBA infamously asked them to remove the Mortal Kombat characters from later ROMs.