Here is the full list of all 40 Roundabout achievements.
In "The Great Hunt", find 6 regions.
Make a huge mistake.
Die 360 times.
Unlocked the Inflatiboat For Cars.
In "Run Like Crazy", get 150 yards away.
Unlocked the Pickup Finder.
Unlocked the Traffic Coner.
Reach 100% completion on a mission.
Unlocked the Reverser Wheel.
Purchase some property.
Purchase something from The Chrome Dome.
Follow a lady into the big smoke.
In "Ball Bouncers", bounce the ball at least 12 times.
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.
Drove straight for Beth.
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.
Purchase a pet eagle.
Complete your first eSports Speedrun Challenge.
Get a better eSports Speedrun Time than the No Goblin team.
In "Death from Above", survive for 30 seconds.
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.
Purchase every property.
Reach 100% completion for the entire game.
Complete an eSports Speedrun without exploding.
Drive the entire "classic" length of Desert Limo without crashing.