Here is the full list of all 40 Roundabout achievements.
Stand still for a minute of silence at The Memorial.
Honk your horn 500 times, then honk your horn 500 more.
Unlocked the Beary Nice Music Box.
Unlocked the Pickup Finder.
Die 360 times.
Aggressively warn a dozen pedestrians with the Trafffic Coner.
Complete your first eSports Speedrun Challenge.
Unlocked the Traffic Coner.
Drove straight for Beth.
Make a huge mistake.
Unlocked the Inflatiboat For Cars.
Unlocked the Reverser Wheel.
In "Run Like Crazy", get 150 yards away.
In "Death from Above", survive for 30 seconds.
Follow a lady into the big smoke.
Purchase some property.
Purchase something from The Chrome Dome.
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.
Survive the Mountain Fair Demolition Derby without exploding.
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.
In "The Great Hunt", find 6 regions.
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 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.