Here is the full list of all 18 Tinertia achievements.
Clear All Worlds in Speed-Run Mode
Clear Slums World
Clear Sewers World
Clear Mines World
Clear Core World
Clear Factory World
Clear Metropolis World
Defeat the ARC
Beat Boss-Rush mode
Earn All Time Medals
Earn All Par Medals
Speed-Run Core without Dying
Speed-Run Mines without Dying
Speed-Run Sewers without Dying
Speed-Run Slums without Dying
Speed-Run Factory without Dying
Speed-Run Metropolis without Dying
Speed-Run ARC without Dying