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
Unlock all levels
Place 1000 traps
Play 100 games
Score 50 comeback points
Enter sudden death 20 times
Play 50 games online
Score 100 solo points
Unlock all characters
Get 50 coins
Kill someone with an arrow 100 times
Kill someone with a hockey puck shooter 100 times
Die 50 times in a black hole
Teleport 50 times
Place 200 traps
Wall jump 1000 times
Play 30 games
Fall into the void 100 times
Unlock a character
Kill people with traps 100 times
Play 10 games
Play 10 games online
Win without any special points
Unlock an outfit
Die with the coin 10 times
Play online with a local friend
Unlock a level
Get 10 post-mortem points
Die on barbed wire 10 times
Glue four blocks together
Attach two blocks together with glue