Pixel Space Program is one of my best, most good projects ever.
Pixel Space Program is a pixel art based series of spaceflight simulation games.
There are 4 mainline entries:
Pixel Space Program
Pixel Space Program HD (aka 1.5)
Pixel Space Program Rewritten (aka 2)
Pixel Space Program 3
Pixel Space Program ReFOURmatted is in development.
Pixel Space Program Classic is the engine used in Pixel Space Program and Pixel Space Program HD.
It is the most fleshed out engine, with full moon landing included, however it is very badly coded and has many bugs.
Pixel Space Program (1) is 10x scale, and a simple rocket can be seen on the side.
Pixel Space Program HD is 5x scale, however all features are identical as it's basically a texture hack.
Pixel Space Program Rewritten is the “black sheep” of the franchise.
Being built on a “clean slate”, it inherited many issues from the Classic Engine, and the new architecture kinda sucked.
A public demo was released, however development stalled, eventually being rebooted into…

Pixel Space Program 3 is the best entry, although lacking Mun and Minmus, it makes up for it with a much more functional game, where it's a lot less likely to break for no reason.
Playable here: https://scratch.mit.edu/projects/1141684246/

Refourmatted is in development right now, but will have many improvements, such as:
An original OST composed by SNVChipehs
Mun and Minmus landings
A Science mode (tested but never fully added in the Classic engine)
Animated engines
And more!