Here is the full list of all 40 Roundabout achievements.
Honk your horn 500 times, then honk your horn 500 more.
Collect every star in every ride.
Purchase every hat and paint job.
Stand still for a minute of silence at The Memorial.
In "Destruction Derby", take out 8 cars.
In "Farming Simulator 1977", complete your farming in under 40 seconds.
Survive the Mountain Fair Demolition Derby without exploding.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
Collect every Cash Stash.
Discover all of the horns.
Accomplish every Sick Jump.
Get a better eSports Speedrun Time than the No Goblin team.
Complete your first eSports Speedrun Challenge.
In "The Great Hunt", find 6 regions.
Purchase every property.
Purchase a pet eagle.
In "Death from Above", survive for 30 seconds.
In "Run Like Crazy", get 150 yards away.
In "Limocide", take out 50 pedestrians.
Unlocked the Multiplier Freezer.
Unlocked the Beary Nice Music Box.
Die 360 times.
Reach a 35x multiplier.
Drove straight for Beth.
Unlocked the Pickup Finder.
Make a huge mistake.
Unlocked the Traffic Coner.
Unlocked the Inflatiboat For Cars.
In "Ball Bouncers", bounce the ball at least 12 times.
Follow a lady into the big smoke.
Reach 100% completion on a mission.
Unlocked the Reverser Wheel.
Purchase some property.
Purchase something from The Chrome Dome.
View the "How's Your Driving" screen outside of the DMV ride. Useful, isn't it?
Collect every star in a single ride.
Revolve over 53,596 times.
Reach 100% completion for the entire game.
Complete an eSports Speedrun without exploding.
Drive the entire "classic" length of Desert Limo without crashing.