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