Here is the full list of all 40 Roundabout achievements.
In "Destruction Derby", take out 8 cars.
Purchase a pet eagle.
In "Death from Above", survive for 30 seconds.
Unlocked the Beary Nice Music Box.
In "The Great Hunt", find 6 regions.
In "Run Like Crazy", get 150 yards away.
In "Ball Bouncers", bounce the ball at least 12 times.
Complete your first eSports Speedrun Challenge.
Die 360 times.
Reach a 35x multiplier.
Drove straight for Beth.
Unlocked the Traffic Coner.
Unlocked the Pickup Finder.
Make a huge mistake.
Unlocked the Inflatiboat For Cars.
Follow a lady into the big smoke.
View the "How's Your Driving" screen outside of the DMV ride. Useful, isn't it?
Unlocked the Reverser Wheel.
Purchase something from The Chrome Dome.
Purchase some property.
Collect every star in a single ride.
Unlocked the Multiplier Freezer.
Survive the Mountain Fair Demolition Derby without exploding.
Stand still for a minute of silence at The Memorial.
Honk your horn 500 times, then honk your horn 500 more.
Revolve over 53,596 times.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
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.
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.
Purchase every property.
Reach 100% completion on a mission.
Reach 100% completion for the entire game.
Complete an eSports Speedrun without exploding.
Drive the entire "classic" length of Desert Limo without crashing.