Here is the full list of all 21 Rollerdrome achievements.
Finish a Match in the Out For Blood Campaign
Complete the main Campaign
Reach the Final
Reach the Semis
Beat the Spider Tank Mk. I without taking any damage
Reach the Quarters
Complete every Tutorial exercise
Finish a Match without taking any damage
Finish your first Match
Play through and finish the Entry Tests
Complete 50% of the Challenges in the main Campaign
Complete 100% of the Challenges in the main Campaign
Finish a Match in a single Combo
Perform a single Combo worth more than 3,000,000
Finish every Match in the Out For Blood Campaign
Complete 100% of the Challenges in the Out For Blood Campaign
Eliminate 2 House Players with a single Z-11 shot
Eliminate 3 House Players with a single Grenade
Finish a level using only Slug Shots
Perform every Grab Trick in a single Match
Perform every Grind in a single Match