Here is the full list of all 30 Fallen achievements.
Encounter 1st Ghost
See the Reaper
Meet Charlie
See The Beast
Kill First Boss
Enter the Grave Yard
Kill Demon King
Meet Master Yuka
Witness the death of Master Yuka
Kill Masko
Hit Red bat in Pick That Pumpkin Map 1
Pick Super Bat Power up in Pick That Pumpkin Map 2
Use Teleporter in Pick That Pumpkin Map 3
Pick Risky Pumpkin in Pick That Pumpkin Map 7
Score 1 in Death Race Map 1
Score 1 in Death Race Map 2
Score 1 in Death Race Map 3
Score 1 in Death Race Map 4
Score 1 in Death Race Map 5
Score 1 in Death Race Map 6
Score 1 in Death Race Map 7
Score 1 in Death Race Map 8
Score 1 in Death Race Map 9
Score 1 in Death Race Map 10
Control All Zones in Ground Control Map 10
Pickup Walls Power up in King Of The Hill Map 8
Control The Hill in King Of The Hill Map 1
Die in Spikes in Head Hunters or Last Man Standing Map 3
Play Level 1 of Spooky World
Play Level 1 Of Jungle World