My favorite items in my video game collection are probably games people wouldn’t care for like a Donkey Kong Country game for Genesis (with original levels!) and Master Fighter, an unlicensed Famicom Street Fighter style bootleg that actually came with an instruction manual. When I was shopping in South Korea, one kiosk had a Game Boy Advance game with Final Fantasy Mario on it. Unfortunately, you can’t try before you buy, but the words Final Fantasy Mario piqued my curiosity enough to buy it.
Here’s Final Fantasy Mario!
Another game featured Maria from Final Fantasy II instead of Mario.
The cartridge also had other NES hacks like Super Mario Bros. with Sonic the Hedgehog swapped in. When you grab a "Fire Flower" (items are orb-like things) he turns into Super Sonic… that shoots fireballs.
Koopa Invaders is Space Invaders with a Koopa Trooper paddle that shoots Mario faces.
This amusing hack puts Ronald McDonald in BurgerTime.