Full list of all 65 Mars Horizon achievements worth 1,180 gamerscore.
The base game contains 59 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 6 achievements worth 180 Gamerscore.
Complete every Milestone mission in a single game
Complete every Research in every Research Tree in a single game
Complete every Research in the Vehicles Tree
Complete a mission using an astronaut above the age of 70
Land humans on Mars in a Joint mission with another agency
Complete the Grand Tour
Launch any vehicle except Sounding Rocket with 50% or lower Launch Reliability
Complete every Research in the Buildings Tree
Win the Race to Mars
Land humans on Mars
Complete every Research in the Missions Tree
Complete all 4 Mars Preparation missions
Hire a Tier 3 astronaut
Land an Exploratory Rover on Mars
Launch a Space Telescope into orbit
Complete a Modular Space Station
Launch any vehicle except Sounding Rocket with 99% Launch Reliability
Complete a Publicised Request Mission using a Celebrity astronaut
Launch a mission using a reusable launch vehicle
Complete a mission task with 30 or more Thrust
Complete a Joint Mission
Complete a mission to any of the Outer Planets
Have a single building with 6 active Positive Adjacency effects
Complete Human in Space, Orbital EVA, Multicrew Orbit, Crewed Moon Landing with the same astronaut
Launch a crewed moon mission using a Saturn V booster
Unlock an Era Completion reward in a Research Tree
Construct a small, medium, and large launchpad
Explode a Sounding Rocket
Successfully launch a vehicle in Terrible conditions
Complete a mission to any of the Inner Planets, excluding Earth
Complete an Orbital EVA
Complete a mission task that requires Drift to be exactly 0
Complete every Bonus Objective on a mission with at least 3 tasks
Complete the Bonus Objective of a mission task that involves Heat
Complete a mission with a Payload that has 99% Payload Reliability
Complete a Challenging Request Mission
Achieve a mission task's Bonus Objective with the last Command of the last turn
Reach the maximum Experience Level for a vehicle part
Launch an animal into Earth orbit
Complete the Bonus Objective of a mission task
Place an Artificial Satellite in orbit
Complete a mission with a Payload that has 50% or lower Payload Reliability
Complete every other Mars Horizon achievement
Launch a human into Earth orbit before April, 1961
Complete the Crewed Moon Landing mission before July, 1969
Land on the Moon before any other space agency
Finish 1st in every Milestone mission in a single game on normal difficulty or above
Succeed a launch using an N1 booster
Launch a vehicle with a 1% chance of Critical Failure... which explodes
Complete a Joint mission with an Antagonistic agency
Send an astronaut on a mission one month before their retirement
Remove every obstruction from your base
Become Allied with all other agencies
Complete a mission task with 50 or more Data
Complete a mission task with 50 or more Comms
Complete a mission task with 1% Payload Reliability at the end of it
Win the Race to Mars on hard difficulty or above
Win the Race to Mars on very hard difficulty
Win the Race to Mars with all 5 space agencies
Win the race to Mars on Iron Core
Fly a helicopter on Mars?!
Successfully land a reusable rocket
Successfully complete the Space Tourism request mission
Explore Mars using the Zhurong Rover.
Successfully completed the Philae Landing mission.