Here is the full list of all 31 Ultimate Chicken Horse achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Unlock all outfits
Score 50 comeback points
Enter sudden death 20 times
Score 100 solo points
Get 10 post-mortem points
Get 50 coins
Play online with a local friend
Place 1000 traps
Play 100 games
Die 50 times in a black hole
Kill someone with an arrow 100 times
Teleport 50 times
Kill someone with a hockey puck shooter 100 times
Play 50 games online
Wall jump 1000 times
Unlock all levels
Play 30 games
Place 200 traps
Unlock all characters
Glue four blocks together
Unlock an outfit
Fall into the void 100 times
Die with the coin 10 times
Unlock a character
Win without any special points
Kill people with traps 100 times
Attach two blocks together with glue
Play 10 games
Play 10 games online
Die on barbed wire 10 times
Unlock a level