SEGA Mega Drive Ultimate Collection

To get this achievement you will have to unlock all of the arcade games. The only notiable one to unlock is the one for finishing the first boss on sonic 2 on 2 player. To get this just plug in a second controller on the the boss fight and beat him. You can check what arcade games you got left to unlock in the museum, to acces this hit B in th main menu.

To get this you must play all arcade titles INCLUDING the extra ones, here's a list of the extra arcade titles and how to get them-

Alien Syndrome
Alien Storm: Reach Mission 3 without losing a life.

Altered Beast Arcade
Altered Beast: Collect 100,000 pts or higher by the end of the first level.

Tip Top
Streets of Rage: Complete 1st Level using all 3 characters.

Fantasy Zone
Flicky: Collect 80,000 points.

Golden Axe Warrior
Golden Axe III: Use magic 10 times.

Phantasy Star
Sonic the Hedgehog 2: Defeat the first boss with two players.

Shinobi Arcade
Shinobi III: Complete first level without using continues.

Space Harrier
Super Thunder Blade: Score over 1,500,000 points in the first level.

Zaxxon
Decap Attack: Collect 5 Bonus coins.