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