I actually realized this about 18 years ago but figured it was worth sharing... With a little effort, you can plug an Atari 2600 joystick into a model 1 Genesis controller port. Since it only has one button it works great for Sonic lol
Yeah, I actually did that with Sonic 2 back in the day
Did you known in TMNT 2 NES you can both grab the pizza at the same time?
Playing around with the switches on the Atari 2600 can make games glitch out. Popeye comes to mind
In Mario 2 NES, on the Clawgrip fight if you crouch in the right corner and throw the rock against the wall you can hit the boss multiple times. Time it well, you can knock him out in one hit! Also, the key will go through any unlocked door. In 1-2 for example, you can take it to the Birdo fight. Finally, in the Wart fight you can jump over him and attack him from the back
In Bayou Billy you can earn power ups for the main game in the practice stages
In TMNT 1 NES in the tight corridor on the approach to Shredder: duck whenever a air soldier approaches and he'll shoot over your head and fly offscreen
Guess this isn't really stuff I just discovered but fuck it I already typed it out