The Mega Man franchise might be on an indefinite hiatus but that didn't stop Capcom from putting in a pretty sweet Mega Man reference in Dead Rising 3. You can unlock both the Mega Man X costume and Mega Buster for Nick to use.
The Mega Man X costume doesn't do anything special for Nick outside of making him look extremely awesome. The Mega Buster though is a decimating weapon that clears out an area of zombies.
To unlock the Mega Man X costume, you have to beat the game on Normal Mode and get the S Rank ending. That means you have to do a few things in the story. First and foremost, when Gary blocks the entrance to the Karaoke Bar, he gives you a choice to either get Rhonda for him, or kill him to get past him. Obviously stick to the former and head out to get her. When you do, they'll be reunited and you're one step closer to the costume. After you beat the game, you'll go into Overtime Mode where you have to destroy a bunch of Hemlock's drones. Once you do, you'll get the good ending, giving you the S Ranking, and thus, the Mega Man X costume.
To unlock the Mega Buster, you have to do pretty much the same thing, except you have to beat the game on Nightmare Mode. Here, the days are shorter, nights are longer and enemies are a bit more aggressive. You won't have as many days to complete the game, so doing side missions becomes impossible. Instead, stick to main story, make sure Nick is fully leveled, and keep on combining guns with blunt weapons, making the Split Shot. That gun alone can win you the entire game.
Once you beat Nightmare Mode, you'll be rewarded with the best weapon in the game.
