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