Wonderful game, I loved navigating the tank across chalenging terrain. Iso-lines on terrain are really useful and give a nice vibe.
The arm is great! Congrats, it works very well for a thing with so many degrees of freedom.
One control issue I ran into often is that the zoom function is unavailable when operating the claw, maybe add some keyboard controls as backup.
While crate stacking, the depth is a bit unclear, which sometimes is a bit frustrating. Maybe a shadow or a shader effect where geometry overlaps would help.
Hope it gets more flushed out with more missions/progression.