It's got the ease of Minecraft and the physics of advanced FPS games like Red Faction! You can build ships and solve engineering problems!
Unfortunately...it also has THE RESOURCE DEMAND OF AUTOCAD!!!
Space Engineers is an awesome game. You can build habitable spacecraft. In the vanilla game (before any mods) you have to build and test your craft. You need to consider conditions, the same thing NASA engineers have to do. Even with the hyper-advanced technology available to you, you need to think.
For example...you have three different kinds of thrusters: atmospheric turbine, hydrogen rocket, and ion plasma. Atmo turbine thrusters are great in atmosphere, but the higher you go, the less they work. Ion plasma thrusters are effective anywhere, but if you're in an atmosphere, their power-to-weight ratio sucks horribly. Hydrogen rockets are powerful and don't have the limits of atmo turbines or ion thrusters, but require a hydrogen tank for fuel, which adds bulk.
However, as an Orbiter veteran, I can tell you that this game offers a great many things which simplify construction. For example, everything has a flight computer akin to the ones on the space shuttle or Apollo commmand module. You have something called an "inertial dampener" which should be called an "inertia inducer." When activated, the inertia system counters your linear motion, bringing you to a stop, providing you have the thrusters to do so. (So if you're in a ship and your retro thrusters are tiny, turn the ship around to bring your main thrust against your motion...and that works.) You don't need to build RCS jets to rotate your craft...you have heavy gyros for that. Put one of those in your ship and you can rotate any direction. You also have solar panels, batteries, and nuclear reactors.
It's thrilling when you can take your own design off the ground and free of planetary gravity.
The major problem I have is not the absence of orbital mechanics...it's the resource demand. Bear in mind, I have something built for AutoCAD, and that program can suck resources for what it does (granted, it does things EXTREMELY well, but you pay a price for it!). However, the software has a memory leak somewhere...If I load saves over the same session, it takes up more and more memory (and I have 16GB on the mainboard!!!). Even an initial startup uses up half of my memory.
While it's a great game it needs some programming work, because not everyone has ludicrous amounts of resources, even in gaming-grade computers.