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