Collection to add realism to the physics of space engineers - primarily proper ship physics (place your engines correctly along center of mass people!), drag and lift, water on planets (boats/subs viable), better traction for rovers (depending on your design) and max speed changes. Your jetpack is no longer as powerful as a hydrogen-fueled rocket; it has good use in moving around something you're building or trajectory adjustments in space, but isn't a global personal transportation system.