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