Here is the full list of all 40 Roundabout achievements.
Unlocked the Beary Nice Music Box.
Collect every Cash Stash.
Purchase every property.
Accomplish every Sick Jump.
Discover all of the horns.
In "Destruction Derby", take out 8 cars.
In "Death from Above", survive for 30 seconds.
Reach a 35x multiplier.
Stand still for a minute of silence at The Memorial.
Die 360 times.
Honk your horn 500 times, then honk your horn 500 more.
Unlocked the Pickup Finder.
Reach 100% completion on a mission.
Drove straight for Beth.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
Purchase a pet eagle.
Unlocked the Traffic Coner.
Make a huge mistake.
Unlocked the Inflatiboat For Cars.
Unlocked the Reverser Wheel.
In "Run Like Crazy", get 150 yards away.
Follow a lady into the big smoke.
In "Ball Bouncers", bounce the ball at least 12 times.
Purchase some property.
Purchase something from The Chrome Dome.
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.
Revolve over 53,596 times.
Complete your first eSports Speedrun Challenge.
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 "The Great Hunt", find 6 regions.
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.