Here is the full list of all 40 Roundabout achievements.
Reach 100% completion on a mission.
Unlocked the Beary Nice Music Box.
Purchase every property.
Stand still for a minute of silence at The Memorial.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
In "Run Like Crazy", get 150 yards away.
Unlocked the Pickup Finder.
In "The Great Hunt", find 6 regions.
In "Death from Above", survive for 30 seconds.
Unlocked the Reverser Wheel.
Die 360 times.
Complete your first eSports Speedrun Challenge.
Unlocked the Traffic Coner.
Drove straight for Beth.
Purchase something from The Chrome Dome.
In "Ball Bouncers", bounce the ball at least 12 times.
Make a huge mistake.
Unlocked the Inflatiboat For Cars.
Purchase some property.
Follow a lady into the big smoke.
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.
Survive the Mountain Fair Demolition Derby without exploding.
Honk your horn 500 times, then honk your horn 500 more.
Revolve over 53,596 times.
Purchase a pet eagle.
Get a better eSports Speedrun Time than the No Goblin team.
In "Limocide", take out 50 pedestrians.
In "Farming Simulator 1977", complete your farming in under 40 seconds.
In "Destruction Derby", take out 8 cars.
Reach a 35x multiplier.
Collect every Cash Stash.
Accomplish every Sick Jump.
Discover all of the horns.
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.