Here is the full list of all 40 Roundabout achievements.
Purchase some property.
Purchase something from The Chrome Dome.
In "Ball Bouncers", bounce the ball at least 12 times.
View the "How's Your Driving" screen outside of the DMV ride. Useful, isn't it?
Collect every star in a single ride.
Unlocked the Inflatiboat For Cars.
Unlocked the Pickup Finder.
Unlocked the Reverser Wheel.
Unlocked the Traffic Coner.
Unlocked the Multiplier Freezer.
Unlocked the Beary Nice Music Box.
Follow a lady into the big smoke.
Make a huge mistake.
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.
Die 360 times.
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 "Run Like Crazy", get 150 yards away.
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.
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.