Kerbal Space Program

Developed by Squad and published by Private Division.
In Kerbal Space Program, you'll be in charge of constructing fully-functional spacecraft to send the alien race known as Kerbals into outer space! 
Make It Fly!
...or don't. You'll have access to a wide variety of parts to assemble a fully-functional spacecraft but it's up to you to make sure they'll actually work! You'll also be able to send your Kerbal crew outside the ships for "extra-vehicular" activities! 
Go, Kerbals!
If you want your little Kerbals to be able to explore space and use the spaceships you crafted, you'll need them to be alive! Hire, manage, and train your crew of Kerbals to make sure everything goes right. 
Explore the Galaxy
Venture all around the solar system, including unique moons and planets with detailed terrains! Then, once you collect valuable information and resources, use them to research and develop new technologies to go to even more places! 
Game Modes
There are three different gameplay modes to experience in Kerbal Space Program!
Science Mode: in this mode, you'll perform space experiments in order to unlock all kinds of new technology and advance the knowledge of the Kerbalkind.
Career Mode: This mode is more focused on strategy, as you'll have to oversee all the aspects of the space program, including construction, strategy, funding, upgrades, and more!
Sandbox Mode: lastly, if you're looking for a more lax experience, you'll be able to free-build any spacecraft you can think of, and all the parts and technology will be unlocked from the beginning!
Steam Deck
If you want to take your space-adventuring with yourself, you can! Kerbal Space Program is playable on the Steam Deck!