The final version:
Heya, just signed up. Been using this site for ages but never actually got involved or made anything myself until now.
First, some background: Nintendo Life posted their April Fools' joke with something that, as a big Luigi fan, I wished was true: http://www.nintendolife.com/news/2013/04/new_luigi_code_to_provide_a_fresh_take_on_virtual_console_classics
The bolded part in the article, Dr. Luigi, got me thinking: Surely someone had done that before, I mean it's such an obvious switcheroo. Plus I play the 8bit Dr. Mario all the time (I have so many copies of it) and even a little change like that would freshen things up, so I searched for a hack...and came up empty-handed. It also hit me that 'obvious' changes like Pauline as the lead in Donkey Kong only came around this year too.
So, having never messed with romhacking before I grabbed a sprite editor and dove in, thinking this would be simple...and ended up spending my whole morning and afternoon on it before I could call the project 'done'. What an interesting trip that was. Here's the result!
By rom-hacking standards it probably isn't much; I just replaced all of Mario's graphics and the two logos. I put a lot of effort into drawing them, though! I tried not to make Luigi look too 'modern', and even consulted other Luigi sprites from other NES/GB games of the time to keep him looking classic but also not looking too much like Mario. Hey, for a first try I'm feeling pretty good about it!
So is it release-worthy? Do you think I need to tweak something? I was also considering adding a little "Year of Luigi Collection" blurb either above or below the title logo and possibly making this a series of relatively simple (but infinitely awesome) Luigi insertion hacks. What do you think? Let me know!