Here is the full list of all 21 Riders of Asgard achievements.
Complete the tutorial
Crash on your head 50 times
Crash on your head 1000 times
Do every trick over the Crazy Canyon
Collect 1000 gold
Crash 50 times in Dunga Forest
Crash 50 times in The Village of Ugladale
Crash 50 times in The Shipyard
Find at least 1 Secret Chest
Find at least 5 Secret Chests
Find all the Secret Chests
Complete a Challenge Run
Survive for at least 1 minute in Survival mode
Break 10 barriers with your hammer
Crash 50 Times in The High Seas
Crash 50 Times in Shipwrecked
Crash 50 Times in the Darkwoods
Crash 50 Times in The Train
Crash 50 Time in The Valley of Giants
Crash 50 Time in The Market
Crash 50 Times in The Floating Hills