Super Mario Land 2 is one of the most iconic Game Boy games, and for the first time, you can play it in full-color thanks to an enterprising ROM hacker. It's amazing how much adding color makes the sprites pop in this game, and I have a new appreciation of the art after seeing the ROM hack in action.
ROM hacker toruzz has taken the 1992 Game Boy game and added a color palette reminiscent of the one you see in The Legend of Zelda: Link's Awakening DX. Super Mario Land 2 DX (as toruzz has titled the hack) also adds the ability to play as Luigi (who has different physics) and removes the lag issues the original game has.
One of the coolest aspects about this hack is that it's actually playable via real hardware. A lot of ROM hacks use programming or assets that can only be used via emulator, but if you have a way to play ROMs on the Game Boy Color this hack will run just like any other GBC game.
To use this hack you'll need the patch for Super Mario Land 2 DX, and a ROM dumped from your legally purchased cartridge of Super Mario Land 2: 6 Golden Coins. You can then use the .ips file with Lunar IPS to patch the ROM. Then you just need a way to play.
Remember to check the law concerning game backups and emulation in your country before trying the above.
I love the work toruzz has done here, and it makes me wonder why Nintendo doesn't go back and clean up a few of its Game Boy and NES classics with some color and bugfixes. There's a ton of awesome games that could really shine again given just a little bit of TLC.