What is there do to in this game?

As far as i know, you can drive around a number of maps and explore. Is this like Rock Simulator?

 

Yeah, pretty much. There are no missions or goals/objectives. You can make some for yourself (such as delivery missions, beat lap times, get through a off-road course with minimal damage etc). They have said that there will be objectives in the future (i can't quote or say anything as i can't remember exactly what was said) along the lines of what i have suggested you can do yourself.

 

Currently, beamng is purely sandbox. No objectives or official game elements. Those will be added in the future. But for now, its basically "use your imagination and have fun". There are a few select maps with timers though. Although i would never put this in the same category as rock simulator, or any other youtube bait "simulator". This is an actual simulator for vehicle physics. Its not perfect yet, but it is in early alpha.