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