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